Git command line changes for WSL

[ssparach]

Summary of the pull request

This PR contains the last set of changes to allow file explorer integration of a WSL git repository. It does this by using WSL command line to obtain all property information from git.

References and relevant issues

https://github.com/microsoft/devhome/issues/3829

Detailed description of the pull request / Additional comments

This PR:

• Uses git rev-parse --show-toplevel to validate a git repository instead of LibGit2Sharp.Repository()
• Uses git -no-optional-locks-branch --show-current to retrieve branch name, detached state
• Adds --branch to RetrieveStatusInformation to obtain branch sha, ahead by value, behind by value and upstream branch info
• Uses rev-parse HEAD to find head commit
• Removes CommitWrapper(LibGit2Sharp.Commit commit) constructor and removes FindLastCommitUsingLibGit2Sharp from CommitLogCache

Note: This PR removes LibGit2Sharp usage where applicable and other unused library using statements. However, it does not completely clean usage of LibGit2Sharp library as the enum definitions from this library are being relied on such as FIleStatus etc. A separate bug has been created to track the complete removal of LibGit2Sharp from the git extension project (i.e. Create custom enum definitions for FileStatus, SubmoduleStatus to remove LibGit2Sharp dependency from git extension project · Issue #3894 · microsoft/devhome (github.com)). This improvement is not blocking to this PR.

Validation steps performed

Build of msix package Unit Testing Validation of functionality in VM

PR checklist

• [ ] Closes #xxx
• [ ] Tests added/passed
• [ ] Documentation updated

[ssparach]

Thanks a lot for reviewing, everyone! I went through the PR comments and did not find any blocking issues. To speed up the selfhost of this functionality, I will go ahead and wrap up this PR now. I will be sure to address the minor suggestions in a future PR.