LibGL: Generate the API wrappers

We now generate all LibGL API wrappers from a single API method
definition list stored in `GLAPI.json`. Since a significant portion of
the OpenGL API methods are relatively consistent variants, we take
advantage of this to generate a lot of these variants at once.

The autogenerated methods check for the non-nullness of the current
`GLContext`, and only perform an action if a `GLContext` is present.
This prevents a crash in ports like GLTron, who assume you can still
call the OpenGL API without an active context.

This increases our API wrapper method count from 211 to 356.

Fixes #15814.

Userland/Libraries/LibGL/CMakeLists.txt

@@ -1,9 +1,10 @@
+include(libgl_generators)
+
 set(SOURCES
     Buffer/Buffer.cpp
     Buffer.cpp
     ClipPlane.cpp
     ContextParameter.cpp
-    GLAPI.cpp
     GLContext.cpp
     Image.cpp
     Lighting.cpp
@@ -19,5 +20,10 @@ set(SOURCES
     Vertex.cpp
 )
 
+generate_libgl_implementation()
+
+set(GENERATED_SOURCES
+    GLAPI.cpp)
+
 serenity_lib(LibGL gl)
 target_link_libraries(LibGL PRIVATE LibCore LibGfx LibGLSL LibGPU)