Android: Allow reporting start to analytics for non-main activity

a1691a4 made it so analytics start events can only be generated when
starting the main activity. However, some users launch Dolphin's
emulation activity from a separate frontend application, bypassing
Dolphin's main activity. This change adjusts the logic so that start
events can be generated if any activity is started after 6 hours of
inactivity. This more closely matches the behavior we had before
a1691a4, while still ensuring duplicate start events aren't generated.

I've also fixed the inconsistent indentation in ActivityTracker.kt.

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/utils/ActivityTracker.kt

@@ -21,11 +21,9 @@ class ActivityTracker : ActivityLifecycleCallbacks {
     }
 
     override fun onActivityStarted(activity: Activity) {
-      if (isMainActivity(activity)) {
         StartupHandler.reportStartToAnalytics(activity.applicationContext, firstStart)
         firstStart = false
     }
-    }
 
     override fun onActivityResumed(activity: Activity) {
         resumedActivities.add(activity)