tests: Add test for required-flatpak versioning

This sets required-flatpak in the metadata to some different versions
and ensure we're properly able or not able to install it.

Additionally it uses some options with multiple versions. This is not
yet supported but I want to test the existing code and make sure it
properly falls back to just using the first element of the list.

Closes: #3112
Approved by: alexlarsson

(cherry picked from commit 62117308c1)
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Gitea Version: 1.28.0+dev-477-g8b6ad49a5f