(Experimental) External CLI plugins -29kb DFU

Idea and plugin loader implementation by @akopachov, thanks!
All commands done except storage and rpc for latency reasons

applications/services/bt/bt_start.c

@@ -0,0 +1,12 @@
+#include <cli/cli_i.h>
+#include "bt_service/bt.h"
+
+static void bt_cli_wrapper(Cli* cli, FuriString* args, void* context) {
+    cli_plugin_wrapper("bt_cli", 1, cli, args, context);
+}
+
+void bt_on_system_start() {
+    Cli* cli = furi_record_open(RECORD_CLI);
+    cli_add_command(cli, RECORD_BT, CliCommandFlagDefault, bt_cli_wrapper, NULL);
+    furi_record_close(RECORD_CLI);
+}