Closes #19137

Description

This PR updates our isGitHubRepository method to not incorrectly identify subfolders of a directory as being repositories and block the user from creating a repository out of subdirectory with the "This directory appears to be a Git repository".

Other thoughts:

• This PR is about unblocking functionality that is available in the git via the command line. But.. if a user is trying to do this, it 1) could be a mistake - it is not common for a user to make a repository in a repository and now as seen in my video below.. maybe a user doesn't realize that the repository is created in a directory at path + name or 2) they really want submodules. This could be an opportunity to instead of showing an error show a "Did you know?" message about submodules and/or a warning..

2. Should we have something in the footer that says. "This will create the "name" repository at "path/name". That way it is clear that a new directory is being added... I get bit by this often enough. Similarly should the error say "This directory" which being beneath the local path input indicates maybe it is just the local path or should it say "The directory path/name" appears to be a Git directory.

Screenshots

Below we see that github/testing is a repository so if I adding testing to the path. It is now checking if github/testing/testing is a repository which it is not.

Release notes

Notes: [Fixed] The "Create a New Repository" dialog allows creation of repositories of repository subfolders.