SimCallManager can access #getDefaultOutgoingPhoneAccount.

This change allows the sim call manager to access the default outgoing
phone account. This is required to allow the sim call manager to register
incoming calls with the platform without requiring the READ_PHONE_STATE
permission.

Bug: 148111849
Test: TelecomServiceImplTest.java
Change-Id: I4d9a87dab2759d916f8a1bba5f8e4a654d5185e5