Cleanup SignalStrength Parcel

Clean up the SignalStrength parcel. This CL
removes redundant constructors, simplifies the
overall initialization process, and stratifies
the components of the parcel into 2 separate
parts: the strength values from RIL, and the
config values provided by the platform.

Bug: 72116430
Test: runtest frameworks-telephony
Change-Id: Id7d2339362270b3911e96094275e1e545d6b581c