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.
3ed3fb05af