Add isSupported implementation for SipTransport

Add implementation for SipDelegateManager#isSupported as well
as CTS tests.

Bug: 154763999
Test: atest CtsTelephonyTestCases
Merged-In: I7fbd39a8ff17c4e947fdbcca148857684faa3252
Change-Id: I7fbd39a8ff17c4e947fdbcca148857684faa3252
11 files changed