To test this, I decided to look into the .gitconfig used for the test and
examine the credential helpers. However, the format of the git command is
`git config --get credential.<URL>.helper`
What's awkward about this is that the <URL> depends on the host the user
specified when running the tests, meaning I'd need to create a key like
credential.https://github.com.helper to access what I need while setting
this up.
There was no functionality for string formatting before, so I added the
command formattedStringToEnv which essentially wraps fmt.Sprintf() and
saves the string to an environment variable.
This allowed me to dynamically create the config key in the test.
