Enable all shared tests in WGSL.

We can now compile all of the shared and intrinsic tests in WGSL.
Some of the tests generate incorrect code, because e.g. they rely on
features which we don't support in WGSL yet (like ES3+ intrinsics),
but the majority appear to be correct.

Change-Id: Ib13e2c1566d951bdadbf676605e81a8e4574ee65
Bug: skia:13092
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/716999
Reviewed-by: Chris Mumford <cmumford@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
141 files changed