Update GnssAssistance AIDL to match framework changes.

- Merge BeidouAlmanac, GalileoAlmanac, GpsAlmanac, QzssAlmanac into
  GnssAlmanac.
- Change the unit of some fields in KeplerianOrbitModel from
  semi-circles to radians.
- Add a comment to clarify that the week number in
  SatelliteEphemerisTime is without rollover.

Bug: 358381377
Test: atest VtsHalGnssTargetTest

Change-Id: I4f712632d39c5e77865662e28bc929669c4e25e9