libmm-glib: separate files for flags and enums types

This allows us to skip needing to include the non-existent
build_string_from_mask() or get_string() counterparts in the
documentation index.

src/mm-modem-helpers-mbim.c

@@ -16,6 +16,7 @@
 #include "mm-modem-helpers-mbim.h"
 #include "mm-modem-helpers.h"
 #include "mm-enums-types.h"
+#include "mm-flags-types.h"
 #include "mm-errors-types.h"
 #include "mm-error-helpers.h"
 #include "mm-log-object.h"

src/mm-modem-helpers-qmi.c

@@ -24,6 +24,7 @@
 #include "mm-modem-helpers.h"
 #include "mm-error-helpers.h"
 #include "mm-enums-types.h"
+#include "mm-flags-types.h"
 #include "mm-log-object.h"
 
 /*****************************************************************************/

src/tests/test-modem-helpers-qmi.c

@@ -25,6 +25,7 @@
 #include <libmm-glib.h>
 
 #include "mm-enums-types.h"
+#include "mm-flags-types.h"
 #include "mm-modem-helpers-qmi.h"
 #include "mm-log-test.h"