[TwigComponent] Add support for anonymous component name resolution in other bundle

[Phil23]

Q	A
Bug fix?	no
New feature?	yes
Deprecations?	no
Documentation?	no
Issues	Fix #1998
License	MIT

In a recent PR (#3169), @andyexeter added support for using index.html.twig as a component template when the component is placed in a directory named after itself. However, it seems to miss the implementation for external bundles. This PR extends the change so that anonymous component templates in other bundles can also use this naming pattern.

[smnandre]

Hi @Phil23

Could you add a few tests for the edge cases... that will mainly be used to decide once and keep the same behaviour afterward.

<twig:Acme:Foo:Index /> 

<twig:Acme:Foo:index />

<twig:Acme:Index:index />

( depending on the various possibilities (there is or not a template, caps / lower) )

Also let's add a line in the CHANGELOG (the one in the src/TwigComponent directory)

Minor/personal note here: this will work (and thank you for this PR by the way 🤝 )..

... I would still not recommand "officially" this trick to bundle maintainers.. or I would recommand them to not abuse it, and keep it "inside" their component structure instead of using this for the "main ones" -- button for instance..
... as the differences with how the Twig and Live component are handled could lead to frustrations I guess.

[Phil23]

@smnandre Thank you for the feedback.

I added several edge cases to the unit test.

I also added the changelog entry. I wasn't sure about the version number, though.

[smnandre]

Thank you for this nice first PR @Phil23 🎉

[Kocal]

Thank you @Phil23.