Reorganize how SkSL includes are parsed and stored

This binds together the IntrinsicMap and SymbolTable for each include to
a single entity, with helper functions that create and return them. Used
a little bit of macro trickery to move all of the standalone/runtime
logic into loadIncludeFile, which drastically reduces boilerplate.

Change-Id: Ic70c0d67967cc614daeab5c50412ab69dcdf2fea
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/324124
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
5 files changed