meta/TexSubImage: Stash everything other than PIXEL_TRANSFER/store in meta_begin

meta/TexSubImage: Stash everything other than PIXEL_TRANSFER/store in meta_begin

Previously, there were bugs where if the app set a scissor it could affect
the area of the texture that was downloaded.  There was also potential that
the framebuffer SRGB state could affect downloads.  This ensures that those
will get saved/restored and can't affect the texture download.

Cc: 10.5 <mesa-stable@lists.freedesktop.org>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=89292
Reviewed-by: Neil Roberts <neil@linux.intel.com>