Support for several dynamic backends options is missing

[acfoltzer]

The initial implementation of dynamic backends built out some core features, but a number of the options on the dynamic_backend_config struct are not yet implemented:

• [ ] connect_timeout_ms
• [ ] first_byte_timeout_ms
• [ ] between_bytes_timeout_ms
• [ ] ssl_min_version
• [ ] ssl_max_version
• [ ] ca_cert
• [ ] ciphers