Set vpn bypassability into VpnTransportInfo

Bypassability is available in VpnTransportInfo now. The value
should be read from VPN config and set to network capabilities
to apps to indicate the bypassability.

Bug: 256775913
Test: atest FrameworksNetTests
Change-Id: I8d59ecf69298e9c4f0f402cbeb7852f7067c0af8