Add api_url and login_url config options

[rtalvarez]

What?

• Adds the ability to override api_url and login_url as part of the oAuth flow.
• Removes the stale codeless/jugglecode dependency as it seems it no longer exists and composer fails trying to fetch it (https://github.com/codeless/JuggleCode is a 404)
• phpstan was complaining about a few things in the file I edited, so I tweaked some type docs to fix it, which in turn made some of the baseline neon definitions not applicable anymore. Seems reasonable to me, but LMK if a preferred method exists

Screenshots (if appropriate)

No screenshots to attach, but I have tested these changes in my consumer app via composer require "bigcommerce/api @dev" and verified the right URLs are being used:

If no custom URLs are provided, https://api.bigcommerce.com and https://login.bigcommerce.com are used. If custom URLs are provided, those are being used

[rtalvarez]

LGTM.

@bookernath I wouldn't rename anything, because the proposed names are consistent with class members and comments used around the code.

Thanks for the pointers, makes sense, I'll leave as is then

Would you mind merging this for me if you have access? It looks like I don't have write access around this side of town. Also not sure if the process for cutting a new release is documented anywhere, I'd be interested in publishing a bump with these changes 👀