Revert "Merge GrContext::init into GrDirectContext ..."

This reverts commit 48d8724097d0b108259c2aef7df8ed1aa08bd574.

Reason for revert: Breaking MSVC bots

Original change's description:
> Merge GrContext::init into GrDirectContext ...
>
> And minor cleanups associated with the initialization of these classes.
>
> Change-Id: Ida0372d0b1a0b8bf5b309814de5418e47ea34fdb
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/324122
> Commit-Queue: Adlai Holler <adlai@google.com>
> Reviewed-by: Robert Phillips <robertphillips@google.com>
> Auto-Submit: Adlai Holler <adlai@google.com>

TBR=robertphillips@google.com,adlai@google.com

Change-Id: I00b2ddaeaef53e3fe05a338c88158cf235f325c4
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/324132
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
5 files changed