* xdsv2: support l7 by adding xfcc policy/headers, tweaking routes, and make a bunch of listeners l7 tests pass
* sidecarproxycontroller: add l7 local app support
* trafficpermissions: make l4 traffic permissions work on l7 workloads
* rename route name field for consistency with l4 cluster name field
* resolve conflicts and rebase
* fix: ensure route name is used in l7 destination route name as well. previously it was only in the route names themselves, now the route name and l7 destination route name line up
Fix issues with empty sources
* Validate that each permission on traffic permissions resources has at least one source.
* Don't construct RBAC policies when there aren't any principals. This resulted in Envoy rejecting xDS updates with a validation error.
```
error=
| rpc error: code = Internal desc = Error adding/updating listener(s) public_listener: Proto constraint validation failed (RBACValidationError.Rules: embedded message failed validation | caused by RBACValidationError.Policies[consul-intentions-layer4-1]: embedded message failed validation | caused by PolicyValidationError.Principals: value must contain at least 1 item(s)): rules {
```
Nitya Dhanushkodi