PBAP Client Call Log

Update PBAP Client to correctly handle cases where a call log has either
an unknown phone number or missing timestamp.  Included are test cases
to verify proper parsing.

Bug: 26760364
Bug: 29230296

Test: runtest bluetooth -c com.android.bluetooth.pbapclient.PbapParserTest
Change-Id: Ibdabd0320f3bdd6dee0d7bd7b5ddd9400219f3d4