Add constraints to AppLabel

[Zeophlite]

Objective

• While working on Extract extract to bevy_extract #22852 , I found AppLabel needed multiple additional bounds ( the largest being L: AppLabel + Default + Clone + Eq + Copy , in total 44 times) - this greatly reduces the readability of that PR
• I tried adding this to AppLabel directly, but AppLabel is really just a label, and the versatility of labels means we can't just add all the above constraints

Solution

• Use AppLabelBase as a derived label, that have a super trait AppLabel with the additional constraints.

Testing

• CI

[mockersf]

I don't understand the need to add an intermediate AppLabelBase trait.

If we need it, we should find a better name for it

[Zeophlite]

I don't understand the need to add an intermediate AppLabelBase trait.

The original AppLabel uses the bevy_ecs::define_label! macro to create that type. I'm unable to add Default to that (might be a skill issue)

If we need it, we should find a better name for it

Yeah I don't love it