Add hint for oneshot property & warning when it will be updated continuously by Force Continuous in `AnimationMixer`

[TokageItLab]

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• Closes https://github.com/godotengine/godot/issues/95684

These properties should not be continually updated, so that warnings are issued when they may occur unintentionally.

Ideally, FLAG_USAGE should be used, but I fear the int value limit as flag, so I append that to HINT;

As I remember only audio and partcle bool value properties should have these, but if there are non-bool value properties in other classes that should have this, they should be in USAGE. If there is such a thing, please let me know.

[fire]

The title and the commit has a typo in English grammar. Force Contunuous -> ???

[KoBeWi]

This should really be a property usage, but I think we can add just only one more usage value🤔 Then again, none of the current ONE_SHOT properties have problem with this being a hint, so we could treat it as temporary solution and think of a fix once an actual problem arises (i.e. conflict with another hint, as properties can't have more than 1 hint). To avoid breaking compatibility in the future, you can unexpose the new hint, with a comment that it shouldn't be exposed, because it's improper solution or something.

[TokageItLab]

For now, note that there is comment that reduz's lgtm on contributors chat. https://chat.godotengine.org/channel/animation?msg=eFmBbXF992AHvW5DM

[Repiteo]

Thanks!