Allow passing in acceptUnvalidated without explicitlySelected

This will allow wifi to tell ConnectivityService that partial
connectivity is acceptable even if the network is not explicitly
selected.

This is needed when the user selects a partial connectivity
network and tells the system to connect to the network, and never
to ask again. In such cases, the system must switch to the
network even if it is not explicitly selected.

Bug: 130766237
Test: atest FrameworksNetTests
Test: unit tests in an upcoming CL
Change-Id: I13465090b7b1c0bf5dc83362387a5428d77b7e1d