SPDX standardizes how source code conveys its copyright and licensing
information. See https://spdx.github.io/spdx-spec/1-rationale/ . SPDX
tags are adopted in many large projects, including things like the Linux
kernel.

This was previously missing for generic (which is used on ARM).

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.

This moves all the byte swapping utilities into a header named Swap.h.

A dedicated header is much more preferable here due to the size of the
code itself. In general usage throughout the codebase, CommonFuncs.h was
generally only included for these functions anyway. These being in their
own header avoids dumping the lesser used utilities into scope. As well
as providing a localized area for more utilities related to byte
swapping in the future (should they be needed). This also makes it nicer
to identify which files depend on the byte swapping utilities in
particular.

Since this is a completely new header, moving the code uncovered a few
indirect includes, as well as making some other inclusions unnecessary.