confbridge: Add support for disabling text messaging.

When in a conference bridge it may be necessary to have
text messages disabled for specific participants or for
all. This change adds a configuration option, "text_messaging",
which can be used to enable or disable this on the
user profile. By default existing behavior is preserved
as it defaults to "yes".

ASTERISK-28841

Change-Id: I30b5d9ae6f4803881d1ed9300590d405e392bc13

main/bridge.c

@@ -3721,6 +3721,7 @@ int ast_bridge_features_init(struct ast_bridge_features *features)
 	}
 
 	features->dtmf_passthrough = 1;
+	features->text_messaging = 1;
 
 	return 0;
 }