Clarify Trace capability nomenclature

[frankmcsherry]

This PR changes TraceReader methods advance_by and distinguish_since, and their read counterparts, to more clearly named methods:

    fn set_logical_compaction(&mut self, frontier: AntichainRef<Self::Time>);
    fn get_logical_compaction(&mut self) -> AntichainRef<Self::Time>;
    fn set_physical_compaction(&mut self, frontier: AntichainRef<Self::Time>);
    fn get_physical_compaction(&mut self) -> AntichainRef<Self::Time>;

The documentation means to be a bit more clear about what these abilities entail.

[frankmcsherry]

The prior method names are still present in #[deprecated] form, so ideally this doesn't break anything for anyone!