Use as_image_copy where possible

[torsteingrindvik]

Objective

wgpu has a helper method texture.as_image_copy() for a common pattern when making a default-like ImageCopyTexture from a texture.

This is used in various places in Bevy for texture copy operations, but it was not used where write_texture is called.

Solution

• Replace struct ImageCopyTexture initialization with texture.as_image_copy() where appropriate

[james7132]

Are there any caveats or benefits to using this API? Or is this purely for code quality?

[torsteingrindvik]

Are there any caveats or benefits to using this API? Or is this purely for code quality?

No caveats- it's equivalent: https://docs.rs/wgpu/latest/src/wgpu/lib.rs.html#3284-3291

So just code quality.