[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/sd-filesystem/sd-filesystem.c

@@ -101,9 +101,7 @@ SdApp* sd_app_alloc() {
     SdApp* sd_app = furi_alloc(sizeof(SdApp));
 
     // init inner fs data
-    if(!_fs_init(&sd_app->info)) {
-        furiac_exit(NULL);
-    }
+    furi_check(_fs_init(&sd_app->info));
 
     sd_app->event_queue = osMessageQueueNew(8, sizeof(InputEvent), NULL);
 
@@ -476,7 +474,7 @@ static void cli_sd_info(string_t args, void* _ctx) {
     }
 }
 
-void sd_filesystem(void* p) {
+int32_t sd_filesystem(void* p) {
     SdApp* sd_app = sd_app_alloc();
     FS_Api* fs_api = fs_api_alloc();
 
@@ -555,4 +553,6 @@ void sd_filesystem(void* p) {
 
         delay(1000);
     }
+
+    return 0;
 }