[gtk] (8 commits) ...Merge branch 'win32-gl-improvements' into 'main'

[Matthias Clasen <matthiasc src gnome org>]

Summary of changes:

  3e9d858... gskrenderer.c: Use GL renderer on Windows by default (*)
  598c7d9... GDK/Win32: Try to fix initializing GLES contexts (*)
  b85aa10... gdkglcontext.c: Ensure EGL contexts are in-sync with shared (*)
  38c17c1... gdkglcontext-win32-wgl.c: Cleanup GL context creation (*)
  6f2848c... Cleanup "GDK/Win32: Try to fix initializing GLES contexts" (*)
  4383989... GDK: Force GLES 3.0+ on libANGLE (*)
  0fe37d1... gdkdisplay-win32.c: Clean up GL initialization further (*)
  68985d4... Merge branch 'win32-gl-improvements' into 'main'

(*) This commit already existed in another branch; no separate mail sent