Rename enums in GrContextFactory to remove "GL"

Also, remove kNative as a separate context type and instead make it an alias for kGL or kGLES based on OS.

GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1845923004

Committed: https://skia.googlesource.com/skia/+/2d9c6f81353597aebf5934547e5cba7a872196fb

Review URL: https://codereview.chromium.org/1845923004
diff --git a/tests/GrPorterDuffTest.cpp b/tests/GrPorterDuffTest.cpp
index 566ec12..b037771 100644
--- a/tests/GrPorterDuffTest.cpp
+++ b/tests/GrPorterDuffTest.cpp
@@ -1148,7 +1148,7 @@
     GrContextOptions opts;
     opts.fSuppressDualSourceBlending = true;
     sk_gpu_test::GrContextFactory mockFactory(opts);
-    GrContext* ctx = mockFactory.get(sk_gpu_test::GrContextFactory::kNull_GLContextType);
+    GrContext* ctx = mockFactory.get(sk_gpu_test::GrContextFactory::kNullGL_ContextType);
     if (!ctx) {
         SkFAIL("Failed to create null context without ARB_blend_func_extended.");
         return;