Add null checker for default sms package name and launch intent for sms package

There is a case that default sms package name is null or launch intent is null. As the API is declared as @nullable it is needed to add null handling

Bug: 383435928
Flag: EXEMPT buf fix
Test: atest CdmaInboundSmsHandlerTest, GsmInboundSmsHandlerTest
Test: manullay run sms test in live network for regression checking
Change-Id: I9a0396d3d3dbb7eec5165344591a7be3bd5103f7