[FEAT] environment variable to open a URL after initial setup is complete

[matthewbrandt]

Is your feature request related to a problem? Please describe.
When TAU is included as part of another app, it would be frustrating that once the user finishes setup of TAU, they are not able to open the setup for the "outside" app without looking in a readme or documentation.

Describe the solution you'd like
When TAU initial setup is completed successfully, redirect the user to the URL stored in an environment variable.

Describe alternatives you've considered
Don't know any other way currently to know that TAU initial setup is complete other than checking the database itself for data in it ;)

[FiniteSingularity]

This should be pretty straightforward, and would be quite useful if someone is building a distributable service/app based on TAU.