formats: Move to src/util/formats, delete main/format_unpack.py
Here it is, at last: Moving the gallium format helpers up to src/util. To demo the utility of doing so, I deleted main/format_unpack.py in favor of the src/util/format/format_pack.py-generated code.
gallium drivers are down 32k of text on x86_64. i965 is up 422k of text. vulkan drivers are effectively unchanged.
I don't like the i965 result, but I think we can get it down (move the height loop out of the individual pack/unpack functions, for example), and things will go down more as we drop the pack functions.
piglit results on skl are fine, intel-ci run still outstanding.