Revert "Get EGLimage functions out of GrGLInterface."

This reverts commit bc233135e4b1da0fd628b5822954a23bf3a1c937.

Reason for revert:
EGLImageTest and TextureBindingTest broken on Windows ANGLE
Build failures on Debian9, unable to link
  ld.lld: error: undefined symbol: eglCreateImageKHR

Original change's description:
> Get EGLimage functions out of GrGLInterface.
>
> Only used in test code which can just directly call these.
>
> Also removed related code in interface assemble/validate generator.
>
> Change-Id: I7e821ebb9328bdd2a54d8ab3af929399ca0517d5
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/213480
> Commit-Queue: Robert Phillips <robertphillips@google.com>
> Reviewed-by: Robert Phillips <robertphillips@google.com>

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

Change-Id: I622fadf22c5d79f5b1d335a8a81455978d49a86a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/213960
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
8 files changed