Rename EmitArgs::fSamplers to fTexSamplers

Renames fSamplers to fTexSamplers in GrProcessor EmitArgs, and renames
GrGLSLTextureSampler to GrGLSLSampler. This will allow us to add a
second array of buffer samplers.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1862373003

Review URL: https://codereview.chromium.org/1862373003
diff --git a/src/gpu/effects/GrMatrixConvolutionEffect.cpp b/src/gpu/effects/GrMatrixConvolutionEffect.cpp
index 21af535..60f518b 100644
--- a/src/gpu/effects/GrMatrixConvolutionEffect.cpp
+++ b/src/gpu/effects/GrMatrixConvolutionEffect.cpp
@@ -86,7 +86,7 @@
                                   domain,
                                   "c",
                                   coord,
-                                  args.fSamplers[0]);
+                                  args.fTexSamplers[0]);
             if (!mce.convolveAlpha()) {
                 fragBuilder->codeAppend("c.rgb /= c.a;");
                 fragBuilder->codeAppend("c.rgb = clamp(c.rgb, 0.0, 1.0);");
@@ -105,7 +105,7 @@
                               domain,
                               "c",
                               coords2D,
-                              args.fSamplers[0]);
+                              args.fTexSamplers[0]);
         fragBuilder->codeAppendf("%s.a = c.a;", args.fOutputColor);
         fragBuilder->codeAppendf("%s.rgb = sum.rgb * %s + %s;", args.fOutputColor, gain, bias);
         fragBuilder->codeAppendf("%s.rgb *= %s.a;", args.fOutputColor, args.fOutputColor);