build: Remove the config.h inclusion from all public headers

Do not include it at header side as it is not part of the installed headers.

Only keep it in cogl-gl-headers.h as it is a private header.

Add it to all the source files that depend on it.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3593>

src/backends/meta-input-settings-dummy.c

@@ -19,6 +19,8 @@
  * Author: Marco Trevisan <marco.trevisan@canonical.com>
  */
 
+#include "config.h"
+
 #include "backends/meta-input-settings-dummy.h"
 
 G_DEFINE_TYPE (MetaInputSettingsDummy,

src/backends/native/meta-renderer-view-native.c

@@ -20,6 +20,8 @@
  *     Dor Askayo <dor.askayo@gmail.com>
  */
 
+#include "config.h"
+
 #include "backends/native/meta-renderer-view-native.h"
 
 #include "backends/native/meta-frame-native.h"