PrivateAddressCoordinator: introduce Dependencies class

This CL introduces the Dependencies class for PrivateAddressCoordinator
to allow changing the TetheringConfiguration in tests. Although in
production code TetheringConfiguration won't change after passed to
PrivateAddressCoordinator, there are unit test cases relying on changing
the configuration at runtime.

Bug: 369282577

Change-Id: I5e42005f85e784c0ce3ac9192248c9e4ed4e6147
5 files changed