[FL-1946] RPC App launch (#758)

* RPC: Add App start, lock status
 - Add RPC commands Application start, lock status acquiring.
 - Write tests for RPC App system.
 - Replace Unit Tests application with CLI command. This is for CI needs and for tests that run application.
* Fix NDEBUG build
* Update PB submodule
* Fix RPC print (ENABLE DEBUG PRINT!)
* snprintf -> string_t
* Fix Hard Fault (early mutex free)
* printf -> string_t, format, enable tests
* Update submodule: protobuf
* Applications: rollback unit test naming scheme.

Co-authored-by: Aleksandr Kutuzov <alleteam@gmail.com>

applications/loader/loader.h

@@ -4,12 +4,19 @@
 
 typedef struct Loader Loader;
 
+typedef enum {
+    LoaderStatusOk,
+    LoaderStatusErrorAppStarted,
+    LoaderStatusErrorUnknownApp,
+    LoaderStatusErrorInternal,
+} LoaderStatus;
+
 /** Start application
  * @param name - application name
  * @param args - application arguments
  * @retval true on success
  */
-bool loader_start(Loader* instance, const char* name, const char* args);
+LoaderStatus loader_start(Loader* instance, const char* name, const char* args);
 
 /** Lock application start
  * @retval true on success
@@ -19,5 +26,8 @@ bool loader_lock(Loader* instance);
 /** Unlock application start */
 void loader_unlock(Loader* instance);
 
+/** Get loader lock status */
+bool loader_is_locked(Loader* instance);
+
 /** Show primary loader */
 void loader_show_menu();