Improve bookkeeping around formats. Hopefully make code less confusing.
- Rename TlutFormat -> TLUTFormat to follow conventions.
- Use enum classes to prevent using a Texture format where an EFB Copy format
is expected or vice-versa.
- Use common EFBCopyFormat names regardless of depth and YUV configurations.
Currently, we use the alpha channel from the EFB even if the current
format does not include an alpha channel. Now, the alpha channel is set
to 1 if the format does not have an alpha channel, as well as truncating
to 5/6 bits per channel. This matches the EFB-to-texture behavior.
