Revert "Move GL's SkSL::Compiler to the GPU (like all other backends)"

This reverts commit cddfce2c24581b3a6b61926cc4d2107721fc9bf2.

Reason for revert: Failing Flutter unit tests with *certain* test orderings.

Original change's description:
> Move GL's SkSL::Compiler to the GPU (like all other backends)
>
> This was the only backend that didn't store the compiler on the GrGpu,
> and also the only one that did lazy-instantiation. Trying to standardize
> this code a bit.
>
> Change-Id: Ibdd1bcc2dc9c3756b46a4c6f0543b5bb20fe135d
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/337716
> Reviewed-by: John Stiles <johnstiles@google.com>
> Commit-Queue: Brian Osman <brianosman@google.com>

TBR=brianosman@google.com,michaelludwig@google.com,johnstiles@google.com

Change-Id: I043ad395472fe20addcc59784aefe9061dae02ba
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/338039
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
7 files changed