[FEATURE] Add OutdatedSubState

[lemz1]

i've noticed that there exists an OutdatedSubState which is never used, so i thought about implementing it.
it checks the project.xml version of the current build and compares it to the project.xml version from the main branch.
this check is only done for desktop versions.

we could also use the latest commit hash from the main branch to compare against, but that be more annoying, so i didnt do the check that way.

(i have noticed that #2631 already implemented the OutdatedSubState, however i dont like that implementation, so im gonna keep this open)

[EliteMasterEric]

As much as I generally like this implementation's use of XML parsing, I have an internal PR which removes the XML entirely in favor of another system which uses Haxe code instead.

The version check file should definitely be a separate file. The code should also definitely use the semantic version checking systems found in funkin.util.VersionUtil.

[EliteMasterEric]

NOTE: This pull request is similar to #2720.

[lemz1]

As much as I generally like this implementation's use of XML parsing, I have an internal PR which removes the XML entirely in favor of another system which uses Haxe code instead.

The version check file should definitely be a separate file. The code should also definitely use the semantic version checking systems found in funkin.util.VersionUtil.

im gonna close this for the time being, since it makes more sense to me to wait for the new version system to be fully implemented