unifyfs-ls util

[rgmiller]

A first attempt at an ls like utility for UnifyFS

Description

Creates a new unifyfs-ls utility. In order to support this tool, this PR adds a new client-to-server RPC and two new API functions. It also adds new unit tests.

Motivation and Context

It would be very useful to have a stand-alone utility that can provide information about files in the UnifyFS filesystem.

How Has This Been Tested?

Tested by running the stand-alone tool and by running the new unit test. Test environment is an Ubuntu workstation.

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Performance enhancement (non-breaking change which improves efficiency)
• [ ] Code cleanup (non-breaking change which makes code smaller or more readable)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [x] Testing (addition of new tests or update to current tests)
• [ ] Documentation (a change to man pages or other documentation)

Checklist:

• [x] My code follows the UnifyFS code style requirements.
• [ ] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [x] I have added tests to cover my changes.
• [x] All new and existing tests passed.
• [x] All commit messages are properly formatted.

[rgmiller]

Marked the PR as a WIP. There's a few TODO comments in the code that I'd like to discuss with reviewers.

[adammoody]

Thanks, @rgmiller !