Need contour to support regex for CORS- alloworigin field

[sri-rajar]

Contour alloworigin field for CORS policy is not supporting pattern matching on domains (like *.vmware.com) .

Envoy has ability to provide regex  support https://www.envoyproxy.io/docs/envoy/latest/api-v3/type/matcher/v3/string.proto#envoy-v3-api-msg-type-matcher-v3-stringmatcher  with safe_regex  option

The ask is for contour to support regex pattern matching for the allowOrigin field in CORS policy.