(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/application.fam

@@ -17,6 +17,15 @@ App(
     sdk_headers=["bt_service/bt.h", "bt_settings.h"],
 )
 
+App(
+    appid="bt_cli",
+    targets=["f7"],
+    apptype=FlipperAppType.PLUGIN,
+    entry_point="bt_cli_plugin_ep",
+    requires=["cli"],
+    sources=["bt_cli.c"],
+)
+
 App(
     appid="bt_start",
     apptype=FlipperAppType.STARTUP,