ResourceImporterLayeredTexture mismatched compress options

[arccoza]

Godot version:

3.2.2

OS/device including version:

N/A

Issue description:

In a recent update the 'Lossy (WebP)' compress option was added to the importer options for ResourceImporterLayeredTexture, but neither the compress enum nor the _save_tex function were updated to match.

The option is added in get_import_options on this line.

But the enum doesn't have that option.

Nor does the _save_tex method.

We've now got a mismatch, where choosing Lossy WebP in the importer UI actually generates Video RAM textures, choosing Video RAM generates Uncompressed, and Uncompressed errors.

UI Option	Actual Option
Lossless (PNG)	Lossless (PNG)
Lossy (WebP)	Video RAM (S3TC/ETC/BPTC)
Video RAM (S3TC/ETC/BPTC)	Uncompressed
Uncompressed	Errors

Steps to reproduce:

1. Select a texture to import as a TextureArray or Texture3D
2. Choose Video RAM compression
3. Check the .import folder for the generated platform specific textures

Minimal reproduction project:

ResourceImporterLayeredTexture mismatched compress options.zip

[arccoza]

There are two ways to fix this: The quick and easy way is to remove the Lossy (WebP) option. The longer way is to actually add lossy compression to the enum and _save_tex method. Which would be preferred?

FYI the importer in 4.0 is quite different, but does include lossy compression.
Also missing from 3.2.2 if lossy is wanted is an option to set the quality of the compression.

[akien-mga]

Removing the extra option should be the way to go for now.

[arccoza]

Ok, would you like a PR against 3.2? It's a very small change.

[akien-mga]

Yes, that would be great :)

[akien-mga]

Fixed by #42045.