Make GrGLPerlinNoise::emitCode easier to read.
Make GrGLPerlinNoise::emitCode easier to read.

Convert many formatted strings to plain old strings.

Favor readability of generator over generated code since
we typically pretty print the generated code if we need
to read it.

Change-Id: I0185cd1133f09d07e8ebd8c959e0397818727611
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/297057
Reviewed-by: Michael Ludwig <cb1f3dd24de0f0b611b26bc28bec758a551d9b7d@google.com>
Reviewed-by: Greg Daniel <39df0a804564ccb6cf75f18db79653821f37c1c5@google.com>
Commit-Queue: Brian Salomon <61fabaaf0876044aeedfd8e351e485c028d69e7b@google.com>

aosp-mirror/platform_external_skia,google/skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,google/skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,google/skia,google/skia,aosp-mirror/platform_external_skia,google/skia