Make groups revisionable

@jidrone I applied your latest patch from Add status, then the current the current patch can't be applied. Can you please update it?

Patch no longer applies to latest 8.x-1.x

$ wget https://www.drupal.org/files/issues/2019-01-31/group-make-revisionable-3029907-3.patch
$ git apply group-make-revisionable-3029907-3.patch
error: patch failed: group.post_update.php:45
error: group.post_update.php: patch does not apply
error: patch failed: group.services.yml:33
error: group.services.yml: patch does not apply
error: patch failed: src/Entity/Group.php:43
error: src/Entity/Group.php: patch does not apply

The patch in #3 applied to 8.x-1.0-rc4 but not 8.x-1.0-rc5 nor 8.x-1.x branch so I've uploaded two re-rolls, one for each in case someone needs.

These are automated re-rolls based on git rebase, there was only one very minor merge conflict between rc4 and rc5, and there were no merge conflicts between rc5 and 1.x branch.

This patch brings down a few additions from the parent ticket's latest patch #2829966-47: Support for Revisions on groups.

See interdiff to identify the changes. A few alphabetical order of use statements and added some tests.

Looking into this as part of sponsored work by Global Game Jam

Straight reroll, no reviews yet.

Finished my code review, need to review tests now.

Keep in mind that since the last patch, core fixed an update problem in taxonomy and menu related to code borrowed in this patch. I've left out said code for now, but for posterity, the issues are:

• #3056543: taxonomy_post_update_make_taxonomy_term_revisionable() and the menu link content equivalent fail when entities have no default translation
• #3052318: Update from 8.6 to 8.7 fails due to corrupt menu_link_content or taxonomy_term entity data

It would need a hook_requirement and an adjustment to the post_update hook to mimic core properly. I could not find any corrupt group entities on my test install, but who knows how people managed to mess up their databases :P

That said, attached patch has the revised code. Mainly dropped deprecated code that slipped in from copy-pasting core code and overhauled the route access check to be more alterable as per #2943471: LatestRevisionCheck overrules any other node access module

Next up: Test coverage.

Whoops, access check was using AccessResult rather than GroupAccessResult. Copy-pasting is bad m'kay?

Also, the fact that above patch goes green shows why we need more tests.

Misclicked in SourceTree... :)

Okay I've asked core maintainers and they recommend adding in the aforementioned safety checks because people somehow get their DBs in bad shape.

That said, our sponsor should not pay for this, given how I would also need to write the update hook tests and all and therefore I suggest we move forward assuming no-one messed up their DB somehow. If we do get reports of people not being able to update, we can have the community come up with a patch by copy-pasting the work done in the two linked core issues.

Focusing on the tests for this issue again.

Wow, writing tests for revisions is so painful. But, after many hours of debugging, here we go.

Changed a small base field typo and pushed. Thanks all!