Asset Packs: Optimize icon loader (#164)

* Original pointer can be const

* Back to const icons

* Missed this one

* Simpler string alloc

* Single allocation and header struct for static icons

* Shared allocation and meta struct for animated icons

* Only try to load if dir exists

* Restructure momentum lib

* Use some internal headers

* Swap icons at draw

* Properly init and free, no more original in icon struct

lib/momentum/settings.c

@@ -1,4 +1,5 @@
-#include "momentum.h"
+#include "settings_i.h"
+
 #include <furi_hal.h>
 #include <rgb_backlight.h>
 #include <flipper_format/flipper_format.h>