Move SkGLContext and some GrGLInterface implementations to skgputest module

BUG=skia:
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Committed: https://skia.googlesource.com/skia/+/fe3456cb006110d045b26ff3f8681b893a757b58

Review URL: https://codereview.chromium.org/1815823002
diff --git a/tests/TestConfigParsing.cpp b/tests/TestConfigParsing.cpp
index 9c030ed..4057a37 100644
--- a/tests/TestConfigParsing.cpp
+++ b/tests/TestConfigParsing.cpp
@@ -9,6 +9,8 @@
 #include "Test.h"
 #include <initializer_list>
 
+using sk_gpu_test::GrContextFactory;
+
 namespace {
 // The code
 //   SkCommandLineFlags::StringArray FLAGS_config1 = make_string_array({"a", "b"})