Add S-NSSAI

* Added support for S-NSSAI within HAL
* Created struct SliceInfo that represents a S-NSSAI as defined
  in 3GPP TS 24.501.
* Added slice info to setupDataCall and SetupDataCallResult

Bug: 169960538
Test: made ims phone call
Change-Id: I8d2c55bece07c599cb7d1ac0d16ad85c0acdeae5