Add `transform::InlinePointerLets` - a Transform that moves all usage of function-scope `let` statements of a pointer type into their places of usage.
Make the HLSL writer transform pointer parameters to `inout`.
Fixed: tint:183
Change-Id: I0a7552fa6cd31c7b7691e64feae3170a81cc6c49
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/51281
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: David Neto <dneto@google.com>