Cache call direction along with call duration when merging calls.

When merging calls we cache their durations so we can apply them to the
conference event package data.  We should also, however, also cache and
apply the call direction (incoming/outgoing) to the conference event
package data for accurate call logging.

Also, when looking up numbers in the cache I found a bug where sip-uri
based CEP participant addresses didn't parse properly.  We have already
solved that problem with the ConferenceParticipant.getParticipantAddress
method which properly converts SIP URI style phone numbers to simple
tel URI based numbers.  So we'll re-use that logic here to avoid the bug.
The consequence of that bug would be that some calls would not get the
cached duration and direction information.

Test: Run all unit tests.
Test: Manual testing using VoLTE conference calls with mix of MO and MT
calls; verify call logging is appropriate.
Bug: 134471046

Change-Id: Ifac55fab64e4bcaf8f9e6b5342ce2281a01c42bd