Move VpnManagerServiceTest and VpnTest to frameworks

These unit tests are closely tied to the source code in
frameworks/base and were incorrectly placed in the connectivity
module. Also update the libraries visibility that are used by
the tests.

Test: atest FrameworksNetTests
Change-Id: I196c33a8bd5b5cdb9d42aea381e900681ff6d25e
8 files changed