Unable to identify anything during the `certificate` phase

I'm trying to conditionally request a client certificate with `kong.client.tls.request_client_certificate()` in the `certificate` phase, however, I don't find anything I can use to identify the request.

Almost none of the methods are available in the `certificate` phase, however according to the docs of the mtls plugin (https://docs.konghq.com/hub/kong-inc/mtls-auth/#client-certificate-request), the SNI should be available.

Is there a way to get the SNI in the `certificate` phase?

Start at the kong.client.tls.request_client_certificate() entry point and compare the certificate-phase API with the SNI behavior described in the linked mTLS documentation. Determine whether an existing identifier is available or whether exposing SNI requires a PDK change; done should include a documented, testable way to identify the request in that phase.

Written by the indexing model from the issue text.