Revert "Take GrContext private, GrDDLContext inherit from GrRecordingContext"

This reverts commit d2daa94edeca88281796524fae45f38f11a7bef2.

Reason for revert: Metaru

Original change's description:
> Take GrContext private, GrDDLContext inherit from GrRecordingContext
> 
> Woo!
> 
> Change-Id: I8d201b709343dc18cad31ea740575285dd035f35
> Docs-Preview: https://skia.org/?cl=317436
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/317436
> Reviewed-by: Robert Phillips <robertphillips@google.com>
> Reviewed-by: Brian Salomon <bsalomon@google.com>
> Commit-Queue: Adlai Holler <adlai@google.com>

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

Change-Id: I9b58dee285fbdc49ebc8e76df5da0fe224cf9787
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/318758
Reviewed-by: Adlai Holler <adlai@google.com>
Commit-Queue: Adlai Holler <adlai@google.com>
11 files changed