Entity reference: Scope direct queries

[defr]

Previously, all the queries where exposed straight on the entity type, not taking into account the bundles on which the field actually appears.

This changes it to keep exposing the base fields on the entity type interface, but expose the configurable fields only on the bundles they're attached to.

[codecov]

Codecov Report

Merging #703 into 8.x-3.x will increase coverage by 0.02%.
The diff coverage is 100%.

@@              Coverage Diff              @@
##             8.x-3.x     #703      +/-   ##
=============================================
+ Coverage      79.51%   79.53%   +0.02%     
- Complexity      1274     1277       +3     
=============================================
  Files            192      192              
  Lines           3158     3162       +4     
=============================================
+ Hits            2511     2515       +4     
  Misses           647      647

Impacted Files	Coverage Δ	Complexity Δ
...gin/Deriver/Fields/EntityReferenceQueryDeriver.php	100% <100%> (ø)	11 <0> (+3)	⬆️
src/Routing/QueryRoutes.php	100% <0%> (ø)	3% <0%> (ø)	⬇️

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[defr]

The reverse hunk makes no sense, sorry about that. Fix coming up.

[defr]

For reverse queries, the situation is more complicated, because each field instance can define its own list of target bundles ; fetching the list of possible target bundles if the entity reference field isn't using the default selection plugin is also going to be problematic. I've reverted that change, and changed the scope of that PR to only be about forward references for now.

[defr]

Sorry for the misclick

[pmelab]

Looks good, thank you very much!