Allow creating AnimatedTextures from the FileSystem dock

[CenTdemeern1]

Describe the project you are working on: N/A

Describe the problem or limitation you are having in your project: Creating AnimatedTexture resources from a lot of frames is slow. Especially when you have 50+ frames, in my case.

Describe the feature / enhancement and how it helps to overcome the problem or limitation: When selecting multiple image/texture files in the FileSystem tab, add an option to "convert to AnimatedTexture", which, when clicked, creates an AnimatedTexture resource with all the frames already loaded in, which is easier than dragging and dropping in 50+ files from the FileSystem tab into the Inspector tab. (Also, please load the frames in lexographic order!)

Describe how your proposal will work, with code, pseudocode, mockups, and/or diagrams:

If this enhancement will not be used often, can it be worked around with a few lines of script?: Not applicable, as this is an editor feature in a right-click menu.

Is there a reason why this should be core and not an add-on in the asset library?: It would be much more accessible when bundled with Godot, making it easier for everyone to add animation.

[Calinou]

I think supporting spritesheets (and documenting how to convert frames to a spritesheet) would be a better way to go about this. I'm not sure if people want to have hundreds of files littered around in their project :slightly_smiling_face:

[Xrayez]

I think the following article just needs to be ported to documentation?

https://godotengine.org/article/atlas-support-returns-godot-3-2

But the proposal asks for AnimatedTexture specifically (additionally, SpriteFrames).