* config: add RemoveRequestHeaders
Currently, we have "set_request_headers" config, which reflects envoy
route.Route.RequestHeadersToAdd. This commit add new config
"remove_request_headers", which reflects envoy RequestHeadersToRemove.
This is also a preparation for future PRs to implement disable user
identity in request headers feature.
* integration: add test for remove_request_headers
* docs: add documentation/changelog for remove_request_headers
* integration-tests: switch to go for backends to support TLS scenarios
* fix apply order
* generate additional tls certs
* integration-tests: tls_skip_verify option
* integration-tests: wait for openid to come up before starting authenticate
* add tls_server_name test
* add test for tls_custom_ca
* increase setup timeout to 15 minutes
* fix secret name reference
* mtls wip
* mtls wip
* add test for client_cert