GnssBatching API, port from Fused Location

New HAL APIs for Gnss location batches,
still to be connected (default implementation)
similarly to this aspect of fused_location.h,
initially as a single client system API.

Bug: 31974439
Test: Ensured it builds and runs GPS & FLP (in Test app & maps)
Change-Id: I27d3fd2cffad25039b006e60c4496a440dc86c13