Add a user status callback to filter out blocked users (similar to node status callback)

Good idea, thanks for the patch!
Seems small and simple enough to not cause any trouble, I'd say. I just have some corrections for the doc comments and the description (we should included the same warning as for the "Exclude unpublished nodes" alteration, I'd say). See the attachments.

Committed.
Thanks again!

Ah, forgot that this of course also needs to be ported …

Pretty easy, I'd say, but would be a (slight) regression if we didn't have it in the first stable release.

Also, instead of porting the processor, we might just want to expand/rename the existing "Node status" processor to cover users, too (and maybe other entity types).

Took my suggestion from #8. The new "Entity status" processor supports nodes, comments and users, and also has better test coverage than the old "Node status" processor.
An update function is included, too, of course, to switch to the new processor. I guess we should also warn about that in the release notes. The update function, once again, does not have test coverage, though. I'd need a good example for how to do that.

Ah, yes, forgot a few things.

Re-roll.

Only nits to pick.

1. +++ b/search_api.install
   @@ -200,3 +200,28 @@ function search_api_update_8102() {
   +      // Mark the resulting configuration as trusted data. This avoids issues
   +      // with future schema changes.
   

   Where does that happen?

2. +++ b/src/Plugin/search_api/processor/EntityStatus.php
   @@ -2,30 +2,33 @@
   +    $supported_entity_types = ['node', 'comment', 'user'];
   ...
   -      if ($datasource->getEntityTypeId() == 'node') {
   +      if (in_array($datasource->getEntityTypeId(), $supported_entity_types)) {
   

   Can we add the comment here about EntityPublishedInterface as well?

3. +++ b/tests/src/Unit/Plugin/Processor/EntityStatusTest.php
   @@ -0,0 +1,156 @@
   +      'multiple datasources' => [NULL, TRUE],
   

   /s/multiple/all/ ?

Where does that happen?

In the next line, by passing TRUE to save().
I just stole the code from some Core update function, probably Block or Views, and that had the same comment (and parameter). Pretty important to include, actually, I guess.

Can we add the comment here about EntityPublishedInterface as well?

I don't see how it would apply there? While it is possible to extract the entity class and check whether it implements EntityPublishedInterface, I really don't think that's worth it. (Also, this only applies to nodes and comments, so we'd have to hard-code users anyways.)
In alterIndexedItems() it would just allow us to combine the two if blocks for nodes and comments, that's all – a pretty trivial change. Using it in supportsIndex(), too, would be a significantly larger change, that would have to be its own feature request (in case someone wants support for another content entity type that implements that interface).

Ah, thanks for explaining.

Thanks again for your input!
Committed.