Add support for native git credential helpers

Please add support for native git credential helpers, including the standard Git Credential Manager (https://github.com/git-ecosystem/git-credential-manager)

We use GCM so that we can enable MFA on hosted Gitlab accounts without having to depend on personal access tokens. All git utilities use it correctly, except for GitKraken.

When MFA is enabled for an account in Gitlab, simple username/password cannot be used when pushing/pulling/cloning git repos. We don't like having long-lived personal access tokens sitting around on people's workstations, so we use GCM to cache short-lived oauth tokens. When a user's oauth token has expired, GCM redirects them to the Gitlab web-ui to provide their username/password and MFA code (or Yubikey). On successful authentication Gitlab generates a short-lived oauth token that is handed back to GCM which caches it and makes it available for future git operations. We would like GitKraken to support this standard git feature :)