Remove DhcpResults from NetworkStack shared lib

Remove the dependency on DhcpResults in moduleutils by moving
toStableParcelable to NetworkStack main code, and fromStableParcelable
to the test only.

Only NetworkStack should be generating DhcpResultsParcelables, and only
the NetworkStack should be using DhcpResults at this point (eventually
the class would move from frameworks/base/core to NetworkStack).

Test: built, flashed, WiFi working
Bug: 149403767
Change-Id: I093fa48967a48f594b242b1e05e7d481fa9ee529