[FL-1818] System setting and debug options. RTC HAL refactoring. (#902)

* FuriHal: RTC API refactoring. System Setting application. FuriCore: adjustable log levels. Minor code cleanup.
* Storage: change logging levels for internal storage.
* FuriCore: fix broken trace logging level

applications/system/system_settings.h

@@ -0,0 +1,18 @@
+#pragma once
+
+#include <furi.h>
+#include <furi-hal.h>
+
+#include <gui/gui.h>
+#include <gui/view_dispatcher.h>
+#include <gui/modules/variable-item-list.h>
+
+typedef struct {
+    Gui* gui;
+    ViewDispatcher* view_dispatcher;
+    VariableItemList* var_item_list;
+} SystemSettings;
+
+typedef enum {
+    SystemSettingsViewVarItemList,
+} SystemSettingsView;