feat: add ssh key authentication support

[shivanshuraj1333]

Adds fix for #1601
related to:
ClickHouse/ch-go#350
ClickHouse/ch-go#1075
ClickHouse/ClickHouse#41109

Summary

Adds ssh key auth support

Checklist

Delete items not relevant to your PR:

• Unit and integration tests covering the common scenarios were added
• A human-readable description of the changes was provided to include in CHANGELOG
• For significant changes, documentation in https://github.com/ClickHouse/clickhouse-docs was updated with further explanations or tutorials

[shivanshuraj1333]

@ernado ptal when you've some bandwidth

[SpencerTorres]

Similar comments to #1596, I think we should try to improve the testing here.

The unit tests can stay where they are, but it would be nice to have an integration test for this. We have a resources folder where we could mount and test SSH auth with the ClickHouse server container.

I like the client options, being able to provide a file path via URL seems convenient for external tools dependent on the driver + a URL. I think the custom signer is more useful though, I don't want to have too many file system operations within the driver so it's good to give the user that option.

I'm actually not familiar with the authentication process with SSH and ClickHouse. Can you provide some more info on the structure of the exchange and the limitations?