Add Capability::EXTRA_STORAGE_TEXTURES_FORMATS

[teoxoy]

This is quite a broad Capability, however since wgpu might enable more storage texture formats via Features::TEXTURE_ADAPTER_SPECIFIC_FORMAT_FEATURES, we should allow the extra ones that the WGSL spec doesn't mandate.

The WGSL Spec mandates the following formats:

r32float
r32sint
r32uint
rg32float
rg32sint
rg32uint
rgba16float
rgba16sint
rgba16uint
rgba32float
rgba32sint
rgba32uint
rgba8sint
rgba8snorm
rgba8uint
rgba8unorm

from https://gpuweb.github.io/gpuweb/wgsl/#recursive-descent-syntax-texel_format

So, we need to gate the others we support behind a Capability:

r8unorm
r8snorm
r8uint
r8sint
r16uint
r16sint
r16float
rg8unorm
rg8snorm
rg8uint
rg8sint
rg16uint
rg16sint
rg16float
rgb10a2uint
rgb10a2unorm
rg11b10ufloat
r16unorm
r16snorm
rg16unorm
rg16snorm
rgba16unorm
rgba16snorm

We can later decide to break down the Capability into finer-grained ones.

[teoxoy]

gpuweb/gpuweb#3837 will expose those texel formats, we shouldn't need a new capability.