[graphite] Restructure how we handle AtlasProvider uploads.

* Moves all the uploads into one call that Device uses
* Moves RasterPathAtlas::reset() to be internal
* Moves TokenTracker update to Device::flushPendingWork

Bug: b/291735945
Change-Id: I47787c0b691b82a2d2bcaca6a802d0434c67c9f5
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/765757
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
8 files changed