Create ModuleLoader class.

This shares some common base-level elements between every compiler.
Modules themselves are not yet shared at this CL.

Change-Id: Ie8697906619751fa8b7a98049641e0e359697ced
Bug: skia:13666
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/571417
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
13 files changed