Require AAD and API env variables to be set on production build of UI

[Ethan-Arrowood]

Do you have a feature request?

Complete the following items then submit your issue:

• [x] Detailed description of feature We should modify the code within the webpack configs so that the env variables WEBPACK_PROP_* are required when building for production. This way we can prevent shipping Client builds that are not properly configured with an AAD provider or an API url.
• [x] What value will this bring to this project? This will allow developers to catch bad builds before shipping them to production. It is not 100% full proof as someone may not use our webpack configs or package.json commands.
• [x] Whether you plan on adding this feature yourself or not I'll be happy to work on this after I finish the rest of P0 items. If I don't get a chance to complete it, it will be a good-first-contributor task.