Media Entity finalish review (disregard if you're not part of the Media Initiative; working around long issue node)

The following review and action items is the result of discussion between @catch, @alexpott, @seanB, @phenaproxima, and myself. Most of it is followup stuff. Enjoy!

Remove from patch into "must" or "should" followups

These things should be removed from the patch so that they can be reviewed on their own without blocking the issue. Each should be mentioned in the change record with a link to the followup issue.

In the case of some parts, we might reduce the scope and add the rest back later; in other cases, the functionality might not need to be in core. But we'll discuss each in a dedicated issue. Be sure to add the notes below to the applicable summaries.

1. Token integration. media_token_info(), test coverage, etc. This is a "must" followup because it is required for pathauto support. From @catch:
   

   do we really need tokens for vid and uuid, even node doesn’t provide uuid.

   This is done in #8 and the follow-up has been filed: #2877378: Add token replacements for Media.

2. Actions integration, including all test coverage for it, configuration, SaveMedia action, etc. This should be a "Should" followup since we are unsure how much contrib needs this. There should also be a related followup for generic entity actions (as per tstoeckler's suggestion early on the issue). From @catch:
   

   The actions are in config/optional but the only thing they depend on is media and system therefore they are always going to be installed. If they are there they should be in config/install.

   Also, in particular:

   SaveMedia::execute() is weird setting changed to 0

   This was copied over from node and may not be needed?
   @catch also notes that the action itself is weird and might not be needed even if we add the media actions in core.
   This is done in #6 and the follow-up has been filed: #2877383: Add action support to Media module.

3. Remove forced validation in Media::preSave() and file a followup to discuss presave validation for Media and/or for entities in general ("Should"): #2877397: Determine when and if media items should validate themselves
   This is done in #19
4. Remove full view mode and "tricky" template title handling. There are many valid usecases for this, but it doesn't necessarily need to be in core. Add a "Could" followup note to discuss whether it should be in core: #2877400: Find a way to make title handling generic in entity templates
   This is done in #19, but reverted. See #25 through #27.

Other followups to file

1. File a dedicated, postponed Media Entity followup for #2696555: On the entity form of revisionable entities, make "create new revision" and "revision log" configurable and add it under "Should" on the roadmap: #2878110: [PP-1] Make revision log and "create new revision" configurable for media items
2. File a "Must" followup to fix Media Entity tests for #2827014: Throw an exception when testing status code or response headers in functional JavaScript tests. From @alexpott:
   

   The problematic test is MediaUiJavascriptTest - there are 4 calls to $assert_session->statusCodeEquals() - 3 of which can be removed but the last needs replacing with an assertion on something like "The media type %name has been updated." being on the page

   The follow-up has been filed: #2878112: Fix Media JavaScript tests to account for changes in JavascriptTestBase

3. File a "Must" followup to review JS tests. From @alexpott:
   

   there's new code to wait for stuff that's not being used. This might mean that they currently have random errors.

   The follow-up has been filed: #2878113: Find possible random errors in Media's JavaScript tests

4. File a "Should" followup to discuss the use of <article>:
   

   Twig templates use ? https://developer.mozilla.org/en-US/docs/Web/HTML/Element/article - I don't think that media items should wrapped in that.

   phenaproxima: Open to suggestions here, but not sure what a more appropriate tag would be.

   seanB: It’s either this, or a plain old div I believe. I think perfectly described that a media item is a ‘self-contained composition in a document’ and ‘independently distributable or reusable’.

   alexpott: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/article the aria roles that are related really do not make me think this is at all related to what is in media and when you put a media entity on a node using entity reference it's going to be wrapped in article tags - inside another article - seems weird.

   This follow-up has been filed: #2878115: Make the HTML wrapper tag for media items more semantically correct

5. The ongoing saga of Media::updateThumbnail() which has been discussed at length on the issue and at the DDD sprint. Mark the darn thing explicitly internal and file a followup to discuss it more ("Should"). Someone should go through the whole issue, the DDD spreadsheet, the DDD agenda/notes, this review's notes, etc. and collect all feedback about it and put it in the followup: #2878119: Whether queued or not, update the media thumbnail and metadata before beginning the entity save database transaction

Things to fix in the patch

1. @naveenvalecha changed "tempstore" to "temp store" in the patch, however:
   

   [ibnsina:drupal | Wed 08:25:38] $ grep -r "tempstore" * | wc -l
         75
   [ibnsina:drupal | Wed 08:25:45] $ grep -r "temp store" * | wc -l
         17
   

   So let's use "tempstore" for now.
   This is done

2. Fix the summary of Media:getThumbnailUri(). It gets the thumbnail's URI, not the media entity's. Also explicitly mark the method internal. @todo also check the issue for other discussion of this method.
   This is done in #19 and #21
3. Rename Media:sourceFileChanged() to Media::has/isSourceFileChanged() (which?) and explicitly mark it @internal.
   This is done in #19
4. In In path_entity_base_field_info() fix the in_array() usage to be strict to avoid bugs.
   This is done in #19
5. Change \Drupal\media\MediaAccessControlHandler::checkCreateAccess() to allow users with 'administer media' to create (and add tests).
   This is done in #19
6. Constructs an ImageFormatter object. C&P error; should be MediaThumbnailFormatter.
   This is done in #19
7. Mark Media::updateThumbnail() @internal explicitly and add an @todo referencing the followup to be added above.
   This is done in #19
8. Add an @todo to the template with <article> referencing the followup to be added above.
   This is done in #19