Updater visual fixes (#2391)

* updater: removed unused code; fbt: fixed build error processing in certain cases
* updater: simplified internal pre-update state
* updater: rebalanced stage weights; fixed progress hiccups

applications/system/updater/updater_i.h

@@ -33,12 +33,6 @@ typedef enum {
     UpdaterCustomEventSdUnmounted,
 } UpdaterCustomEvent;
 
-typedef struct UpdaterManifestProcessingState {
-    UpdateManifest* manifest;
-    FuriString* message;
-    bool ready_to_be_applied;
-} UpdaterManifestProcessingState;
-
 typedef struct {
     // GUI
     Gui* gui;
@@ -49,7 +43,7 @@ typedef struct {
 
     UpdaterMainView* main_view;
 
-    UpdaterManifestProcessingState* pending_update;
+    UpdateManifest* loaded_manifest;
     UpdatePrepareResult preparation_result;
 
     UpdateTask* update_task;