config: Implement preferredAuthentications option
PreferredAuthentications is currently mapped to SOC_UNSUPPORTED, it is silently discarded when parsed from ~/.ssh/config, this patch will promote it to first class option, so that when cli is implemented by enabling preferredauthentications user can restrict which authentication methods the client will attempt.
Checklist
- Commits have
Signed-off-by:with name/author being identical to the commit author - Code modified for feature
- Test suite updated with functionality tests
- Test suite updated with negative tests
- Documentation updated
Reviewer's checklist:
- Any issues marked for closing are addressed
- There is a test suite reasonably covering new functionality or modifications
- Function naming, parameters, return values, types, etc., are consistent and according to CONTRIBUTING.md
- This feature/change has adequate documentation added
- No obvious mistakes in the code