Reduce ambiguity of trace from intent to launch activity

Because the launching activities can be floating/translucent/
in different displays/in multiple window mode, there could be
multiple launching traces at the same time.

The trace processor relied on
"MetricsLogger:launchObserverNotifyIntentStarted" and
"MetricsLogger:launchObserverNotifyActivityLaunchFinished",
which didn't provide enough information to know which startup
it belongs to.

With keeping the old trace for migrating, a new async trace is
added: launchingActivity#$seqId. It has the same meaning as
the "Android App startups" by trace processor. And there will
be another trace when the launch is done to indicate the result.
E.g.
 Activity not found:
   launchingActivity#1:failed
 Becomes invisible before reporting drawn:
   launchingActivity#1:canceled:the.pkg.name
 Successful shown:
   launchingActivity#1:completed:the.pkg.name

So the trace processor can search "launchingActivity#$id:completed:"
to get the launched package name and associate "launchingActivity#$id"
to show directly.

Bug: 222576471
Test: Launch an app with
      "external/perfetto/tools/record_android_trace am".

Change-Id: Ifa78e04f79605db27d7fd2a5f582d286ceae2a13