It is common in application to need the host, for example for redirect callbacks using oauth, or for automated CORS restrictions, etc.

This PR adds the host settings and introduces a pattern for settings validation based on environments. Within this pattern validation it adds helpful checks over CORS and the definition of hosts for staging and production.

It is important to show that the pattern also does not fix things for the user or performs changes to their settings based on other settings, i have always found that is better to give the feedback to the user and let the user decide instead of performing modifications at runtime without visibility to the user. That is why in the validation there should only be messages warnings/errors and no modification of the settings.