Rename apexDepsMutator to apexInfoMutator

Generally ...DepsMutator methods add dependencies between modules but
the apexDepsMutator does not which can be confusing. This renames
apexDepsMutator to apexInfoMutator and adds some extra documentation to
clarify its function. It also renames the registered name for the
mutator and its associated providers from apex_deps to apex_info.

Test: m nothing
Bug: 171061220
Change-Id: Ic074a281215b23e982448ccff7ac075236123bee