[FL-872] Furi, API-HAL, App-Loader cleanup and improvements (#334)

* Furi: replace obsolete furiac_exit with osThreadExit, drop obsolete apis and test. Rename systemd to flipper and move to separate file, cleanup. ApiHal: Rename timebase to os and move freertos hooks there, move insomnia api to power module.
* Furi: new thread helper
* Furi: cleanup thread documentation
* Flipper, AppLoader: update to use FuriThread. Update tasks signatures to match FuriThreadCallback signature.
* F4: rename API_HAL_TIMEBASE_DEBUG to API_HAL_OS_DEBUG
* Applications: rename FuriApplication to FlipperApplication, use FuriThreadCallback signature for apps.
* C++ app template sample, new exit method

applications/irda/irda.c

@@ -234,7 +234,7 @@ void init_packet(
     state->packets[index].command = command;
 }
 
-void irda(void* p) {
+int32_t irda(void* p) {
     osMessageQueueId_t event_queue = osMessageQueueNew(32, sizeof(AppEvent), NULL);
 
     State _state;
@@ -262,7 +262,7 @@ void irda(void* p) {
     ValueMutex state_mutex;
     if(!init_mutex(&state_mutex, &_state, sizeof(State))) {
         printf("cannot create mutex\r\n");
-        furiac_exit(NULL);
+        return 255;
     }
 
     ViewPort* view_port = view_port_alloc();
@@ -316,7 +316,7 @@ void irda(void* p) {
                     osMessageQueueDelete(event_queue);
 
                     // exit
-                    furiac_exit(NULL);
+                    return 0;
                 }
 
                 if(event.value.input.type == InputTypeShort &&