anv: Allow storage on all formats that support typed writes

anv: Allow storage on all formats that support typed writes

In particular, this gives us B8G8R8A8_UNORM storage support which is
useful for writing WSI images from compute shaders.  These formats can
only be accessed in a spec-compliant way by decorating the variable
NonReadable in the SPIR-V (writeonly in GLSL).  If the client doesn't so
decorate the variable, it'll get the null surface state where reads
return 0 and writes are ignored.

Tested-by: Simon Ser <contact@emersion.fr>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10624>