Add a filter field to the animation editor to allow filtering tracks

[Arnklit]

Describe the project you are working on

A 2D game in production

Describe the problem or limitation you are having in your project

It becomes difficult to work with animations when they have a lot of tracks, being able to filter them would be very useful.

Describe the feature / enhancement and how it helps to overcome the problem or limitation

Add a filter field similar to the scene or FileSystem docs.

Describe how your proposal will work, with code, pseudo-code, mock-ups, and/or diagrams

Mock-up

I don't think the "Add Track" is very needed, we just have the plus for Add Node, so the filter field could be there.

If this enhancement will not be used often, can it be worked around with a few lines of script?

This would be used often.

Is there a reason why this should be core and not an add-on in the asset library?

This is about improving the default editor user experience.

[Arnklit]

This is also mentioned on this tracker issue. #6681