Add mtls to benthos http_server

[KevinJoiner]

Issue: redpanda-data/connect#2317

2 main changes

1. Update the http_server input and output to use the shared TLS object and deprecate cert_file and key_file settings
2. Update the Shared TLS Object to have the ability to handle mutual TLS verification.

Notes

For servers client_certs doesn't really make sense so I made a separate configSpec that uses the name server_certs

[CLAassistant]

All committers have signed the CLA.