This CL adds const-eval for the `acosh` test case. The generation of
`f16` values into test files is also fixed because `acosh` requires the
value to be `>= 1.0`
Bug: tint:1581
Change-Id: Iba2ca4d9d114034845475679346f042c8c66e571
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/109341
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Dan Sinclair <dsinclair@chromium.org>