Implement initial calling in NUI Voicemail

When a user presses the phone icon in NUI voicemail, we should make a phone call.
This does not handle phone account handling and disabling showing the phone icon for unknown numbers (tracked in b/72449247 and b/72449246)

Bug: 72449869
Test: Unit test
PiperOrigin-RevId: 183318358
Change-Id: I075ae79ec6896f2b9244f990bd2a01493c495e07
1 file changed