This PR solves an issue when using texture pools with textures that are not
natively supported by the device. In the previous implementation the
internal `Texture::format_` was changed. Any check if the texture could
be reused would fail as its format would be different that the requested one.
This PR fixes this by separating the requested format `Texture::format_` and
how it is stored on the GPU `VKTexture::device_format_`.
This solves the next artifacts:
* Workbench flickering artifacts on AMD/Intel GPUs
* Workbench TAA on AMD/Intel GPUs
* Overlays were not always drawn fully solid
Pull Request: https://projects.blender.org/blender/blender/pulls/114697
cc04bcd792