Fix music app :

- Enable LVGL animation (and disable groups, which were not used), and set the speed.
 - Fix disc animation and progress display by initializing lastIncrement at 0 (a random value will be used otherwise, in release build)

src/displayapp/screens/Music.h

@@ -76,7 +76,7 @@ namespace Pinetime {
         /** Last length */
         int lastLength;
         /** Last time an animation update or timer was incremented */
-        TickType_t lastIncrement;
+        TickType_t lastIncrement = 0;
         
         bool playing;