cleanup: Stop allowing deprecated Cogl API usage

Allow only specific files to use those deprecated APIs making
it easier to find where deprecated APIs are still in use
and avoid introducing new usages without being noticed

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3400>

src/backends/meta-stage-impl.c

@@ -25,6 +25,8 @@
  *  Emmanuele Bassi
  */
 
+#define COGL_DISABLE_DEPRECATION_WARNINGS
+
 #include "config.h"
 
 #include "backends/meta-stage-impl-private.h"