Support sharing promise images between DDLs

- Migrate our code to SkImage::MakePromiseTexture
- Have DDLTileHelper share one SKP and one set of promise images across all tiles.
- Disallow on-the-fly allocation of mips for promise textures.

Bug: skia:10286
Change-Id: Ie35976958454fc520f3c9d860e6285441260c9f7
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/291938
Commit-Queue: Adlai Holler <adlai@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
13 files changed