Refine differential fuzzer and fix parsing divergences

Adds new features to the differential fuzzer like comparing values only when the option is explicitly mentioned in the fuzzer input config file.

It fixes the bugs found by the differential fuzzer.

• Ensures command-line options take precedence over config file options
• Adds ssh_config_get_path to parse path based options like IdentityFile, UserKnownHostsFile, GlobalKnownHostsFile
• Strictly rejects unclosed quotes

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
• The project pipelines timeout is extended at least to 2 hours.

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