Expose entry/exit bandwidth criteria APIs for VCN templates

This change adds additional criteria for bandwidth in both the
upstream and downstream directions, ensuring that a minimum quality
bar can be guaranteed for VCN underlying networks. Both directions
support separate entry/exit criterion to allow for hysteresis.

Bug: 205343355
Test: atest FrameworksVcnTests
CTS-Coverage-Bug: 209498272
Change-Id: I61c8469380551e673d91f9a4428d21a40f164841