DEV: Function to get baseUri from get-url helper

[markvanlan]

@eviltrout This is so that I can get the subfolder path. I didn't want to export the variable, so that it cannot be set outside of the get-url file, so I wrote a get function.

[eviltrout]

Why do you need this though? So far other code has avoided it so I am curious.

[markvanlan]

@eviltrout This returns just the subfolder path, if one is present. It is useful to me in my Plugin Adventures ™️, and seems generally useful. Not sure a cleaner way to get just the subfolder path otherwise!

[eviltrout]

You can call get-url "/" right?

[markvanlan]

@eviltrout 🤦