Add a way to expire/recycle a texture in wgpu-core

[nical]

This is needed for Firefox to implement the canvas presentation efficiently using textures. We must be able to:

• Mark a texture as expired which from the user's point of view is equivalent to destroying the texture.
• Recycle the texture memory without allowing old references to the expired textures to affect the recycled versions.

A possible approach is to add a texture "renaming" in wgpu-core which would snatch the hal texture and place it in a new wgpu-core texture. It would leave the old wgpu-core texture alive and unusable and references to it wouldn't be able to affect the texture.