Revert of Add a class representing texture swizzle. (patchset #6 id:100001 of https...

Revert of Add a class representing texture swizzle. (patchset #6 id:100001 of https://codereview.chromium.org/1567733005/ )

Reason for revert:
Shader compilation failures when implicitly converting vec4 to float.

https://uberchromegw.corp.google.com/i/client.skia/builders/Test-Win8-MSVC-ShuttleA-GPU-GTX960-x86_64-Debug/builds/3266/steps/dm/logs/stdio

https://uberchromegw.corp.google.com/i/client.skia.android/builders/Test-Android-GCC-Nexus6-GPU-Adreno420-Arm7-Debug/builds/3154/steps/dm/logs/stdio

Original issue's description:
> Add a class representing texture swizzle.
>
> Store config swizzle GrGLCaps and shader swizzles in GrGLSLCaps.
>
> Remove GrTextureAccess's swizzle and update users of it to swizzle in their shader code.
> GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1567733005
>
> Committed: https://skia.googlesource.com/skia/+/1a1efeacf7cc94a8c2977114dfe230fed3efc105

TBR=egdaniel@google.com,bsalomon@google.com
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/1569393002