Add a Hash() and Equals() methods to sem::Type.
Have sem::Manager (which should be called sem::TypeManager) derive from
utils::UniqueAllocator. This now uses the Hash() and Equals() for uniquely
constructing semantic types instead of building strings and comparing those.
Bug: tint:1383
Change-Id: I5e3229bd087391ac594d333a0ab4232cfcddf54d
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/82743
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: David Neto <dneto@google.com>