Add APIs for network validation feature.

Adds a feature API that allows the QualifiedNetworkService to request
network validation. Request network validation to the data network in
connected state corresponding to the given capability and add the
network validation state to PresiceDataConnctionState in response.

The DataService API that requests validation is also added. When a
network validation request is submitted, the request validation API
is returned imediately and the statuses or results are notified in
the DataCallResponse.

Bug: 299346675
Test: atest FrameworksTelephonyTests
Change-Id: Ifbf6034c0a032ee3551b72025c572d06b53fe810