Add bugreport pre-dump functionality

Allow apps to trigger the dump of certain critical data, e.g. data stored in short
ring buffers that might get lost by the time a bugreport is requested.

Then, a bugreport request can specify whether the pre-dumped data should be used.

Fixes: 205138504
Test: atest com.android.os.bugreports.tests.BugreportManagerTest
Change-Id: I55c7b53e235ebf2baa694e6fdc4e4a321a459c8b