Unix file metatadata

[adrazilo]

Proposed changes

This PR addresses Issue: The metadata command is missing from the mock server.

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

PR Checklist

Please delete options that are not relevant.

• If the changes in this PR are meant for the next release / mainline, this PR targets the "staging" branch.
• My code follows the style guidelines of this project (see: Contributing guideline)
• I have commented my code, particularly in hard-to-understand areas
• New and existing unit tests pass locally with my changes
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works, or describe a test method below

Testing

To test this feature, please consider the following test conditions:

1. You attempt to get the metadata of an existing file
2. You attempt to get the metadata of an existing folder
3. You attempt to get the metadata from an existing sub-path
4. You attempt to get the metadata of a sub-path that does not exist

Further comments

This is not a relatively large change but will further enhance the mock server for learning purposes.