Texture Padding in tileset causing visual glitches

### Tested versions

- Tested in latest stable 4.2.1 build only.

### System information

Windows 11 - Godot 4.2.1 - Vulkan Mobile renderer (Same happens in forward +)

### Issue description

First of all, the Tilemaps I add to my tileset always become transparent. To fix this issue I have to disable "Use Texture Padding" as seen here:


And here with the option checked:


Now, after this "quick fix", when play testing I have many lines between the tiles on screen, as shown here:


What I tried to fix this:

- Set filter to nearest
- Import all textures as Vram compressed and high quality enabled

Now what half fix it:

Reimport the texture as lossless and set to generate mipmaps. The problem is, apart from not being ideal for a mobile game, while Texture padding now works, I still have few lines in some tiles like here:


Unfortunately I cannot share my tileset since it's a paid asset with licensing, but I'll do my best to add more to this discussion.

Edit:

Now I've noticed that after setting back to Vram compressed I get an error in the editor "Cannot blit_rect in compressed or custom image formats." Which is the culprit of not being able to use a VRAM compressed image and texture padding. Still that brings the line bugs from above.

### Steps to reproduce

Import a vram compressed texture in a tileset.

### Minimal reproduction project (MRP)

Can't share I'm afraid.

Start by importing a VRAM-compressed texture into a Godot tileset with Use Texture Padding enabled, using the reported Windows 11 and Godot 4.2.1 renderer setup if available. Check the editor error about blit_rect and the visible lines or transparency between tiles; done means texture padding works without the error or visual glitches while preserving the relevant mobile texture workflow.

Written by the indexing model from the issue text.