Statsd broadcasts when it is alive

To send configurations and PendingIntents to statsd, statsd must first
be alive. In particular, a PendingIntent must be resent to statsd each
time it starts (they are not stored, since reboots make them expire
anyway). Therefore, statsd needs to send a broadcast to inform them of
its starting.

The broadcast receiver will require DUMP permission.

Bug: 72450885
Bug: 70389379
Test: manually confirmed broadcast is sent
Change-Id: I47c130130342465a50cd625bdb135855d5d04f6e