[Request] AnimatorState Attribute

[TiredOfEverything]

An attribute that fills a dropdown with all the names of the possible Animator states for an Animator.

[TylerTemp]

I've implement one on my own project. Though I did not make it a standalone one, but here you can change it as one you need:

1. the struct itself, not need for modification: https://github.com/TylerTemp/SaintsField/blob/master/Runtime/AnimatorState.cs

2. the attribute, delete the inherented interface and non-need properties: https://github.com/TylerTemp/SaintsField/blob/master/Runtime/AnimatorStateAttribute.cs

3. the drawer: https://github.com/TylerTemp/SaintsField/blob/master/Editor/Drawers/AnimatorStateAttributeDrawer.cs

   1. change SaintsPropertyDrawer to PropertyDrawer
   2. change GetFieldHeight to override GetPropertyHeight and adjust parameters as needed.
   3. change DrawField to override OnGUI and adjust parameters
   4. delete all not-need functions, extra information helper, error handings, etc.

And should do the work