This class is very large, so factoring it out into its own seperate
file.
Also renaming it to InspectorBuilder, in anticipation of adding tests
that don't build their state through explicitly calling into the
ProgramBuilder.
BUG=tint:967
Change-Id: I316458a969479200edf6962ab2008180f9a1e7e2
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/57800
Auto-Submit: Ryan Harrison <rharrison@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Ben Clayton <bclayton@google.com>