Use more specific version of LogDataType.TEXT

Use LogDataType.BUGREPORT, LogDataType.LOGCAT, etc, where it makes
sense.  This is to allow the inspect bug result reporter to correctly
parse these files as they're uploaded.

Also, add BugreportCollectorTest to unit test suite and fix those unit
tests.

Change-Id: I486d475f63ef98200a2a4bc4e8674408a0975081
23 files changed