Tests: compile into a single executable

[lenemter]

Closes #2833

Achieves the same performance boost as #2833, but doesn't introduce unnecessary #if conditions

[leolost2605]

Makes sense to me! A few comments :)
Also maybe we should use the glib.test built in way to specify which tests to run? https://valadoc.org/glib-2.0/GLib.Test.init.html says we can just use -p to specify what to run. So we would just construct all testcases, put them in an array and then call test.init and test.run. This would also automatically give us more complete and finegrained control, e.g. to not only specify tests but also skip some, etc. We could also keep the name property if we maybe want to name them differently because we don't rely on the type name then.

[lenemter]

@leolost2605 I don't think it's worth adding name field, at least until we really need it. Currently it's just an unneeded repetition in the code

[lenemter]

@leolost2605 for some reason this broke tests for mutter 50. I pushed a commit with a fix to this branch but let me know if you want to merge it separately and I'll create a new PR

[leolost2605]

Looks good, just a few more comments :)

@leolost2605 for some reason this broke tests for mutter 50. I pushed a commit with a fix to this branch but let me know if you want to merge it separately and I'll create a new PR

Yeah seems like we were doing remove_child (null) there so makes sense. If you clean up the commit history and add the fix as the first commit I think it's fine to merge with this

[lenemter]

@leolost2605 Done!