Add a new Naga feature, `"compact"`, which adds a new function
`naga::compact::compact`, which removes unused expressions, types, and
constants from a `Module`.
Ensure that each distinct type occurs only once in `Module::types`, so that we
can use `Eq` on `Type` or `TypeInner` for type equivalence, without being
confused by differing `Handle<Type>` values that point to identical types.
This removes a number of duplicate types from the ir snapshots.
Fixes#1385.
* Resurrect texture_storage_* tests
* Test parsing of `var<storage,write>`
* Default storage textures to READ
* Restore default features
* Fix glsl/hlsl/msl/spv front and back ends
* Add missing test outputs
* All-around fixes for the storage access
Co-authored-by: Dzmitry Malyshau <kvarkus@gmail.com>
