Block Support: Add unit tests for Elements support.

[dmsnell]

Adds additional unit tests to confirm the behavior of elements block supports when certain conditions aren't met.

Trac ticket: #59578

Follow-up to #59544

Adds additional unit tests to confirm the behavior of elements block supports when certain conditions aren't met.

thanks again @aaronrobertshaw - I made it easy and simply adopted your patch. we can see if @felixarntz and @spacedmonkey are happy with this, as I was simply trying to follow-up with their requirements from last week. if they are, I don't feel like I need any props on this patch since, although I offered some tests of my own flavor, this patch is neither motivated by own my work or the product thereof 🙃

[flixos90]

In 56828:

Editor: Add further test coverage for wp_render_elements_support().

Props dmsnell, aaronrobertshaw.
Fixes #59578.

Committed in https://core.trac.wordpress.org/changeset/56828