Move atlas manager creation to GrContext derived classes

This CL relies on: https://skia-review.googlesource.com/c/skia/+/108001 (Fission GrAtlasGlyphCache in two)

TBR=bsalomon@google.com
Change-Id: Ic3f91cea2238221b970f8ebbda99b10202925cd8
Reviewed-on: https://skia-review.googlesource.com/110621
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
4 files changed