Caps callback should be called when underlying networks are changed

Add a test to check if onCapabilitiesChanged will be called when
the underlying networks are changed.

Bug: 191918368
Test: atest CtsHostsideNetworkTests:HostsideVpnTests
Change-Id: I8dfb16e01199d41b1b65f69e129ec40e37f9ab0f
5 files changed