APIs to configure capabilities in VCN cell network template

This commit exposes APIs enabling caller to configure required
and forbidden capabilities in the VCN cell underlying network
template so that a cell network MUST match the capability
criteria to be selected as the VCN's underlying network.

Bug: 245618320
Test: make update-api && make
API-Coverage-Bug: 262448529
Change-Id: I3da7afab85f338f147707f724133a83fa08df4a5