Added new Forwarded header support for Request::getClientIps

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #11073
| License       | MIT
| Doc PR        | no
@tony-co ``[2001:db8:cafe::17]:4711`` as header should return ``2001:db8:cafe::17`` for the IP, not ``[2001:db8:cafe::17]``, and it will be accepted. The square brackets are not part of the IP. They are only part of teh IP+port notation, because there are ``:``in the IP itself