[graphite] Store ResourceProvider on Recorder instead of Gpu.

By being on Recorder, more calls can directly access the ResourceProvider
without needing the Context or Gpu. A different ResourceProvider is
created for each Recorder. Each ResourceProvider stores a ref to the
GlobalCache so that it can access shared resources. Eventually each
ResourceProvider will also have its own ResourceCache for all non shared
Resources.

A big win of this change is that Context can be removed from Recorder.

Bug: skia:12754
Change-Id: Ib6ac71c617de4d6b6b2ac4956580e65d4d7e6f7a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/502637
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>