mesh: add ComputedImplicitDestinations resource for future use (#20547)
Creates a new controller to create ComputedImplicitDestinations resources by
composing ComputedRoutes, Services, and ComputedTrafficPermissions to
infer all ParentRef services that could possibly send some portion of traffic to a
Service that has at least one accessible Workload Identity. A followup PR will
rewire the sidecar controller to make use of this new resource.
As this is a performance optimization, rather than a security feature the following
aspects of traffic permissions have been ignored:
- DENY rules
- port rules (all ports are allowed)
Also:
- Add some v2 TestController machinery to help test complex dependency mappers.
Co-authored-by: R.B. Boyer <4903+rboyer@users.noreply.github.com>