Updating auth to be compatible with segmented frontend/backend

[mustafa-tariqk]

What does this PR do?

Add CORS support across the board, update auth to work if frontend/backend in different places (i.e. port 3000/8080 or even diff websites)

Also changed testing to be an env variable vs set in app.py

Github Issue Number

Resolves: #57 #74

Relates to: n/a

Warning: Introduces breaking changes. Format future fetch requests like the following

            fetch('http://localhost:8080/start_chat' + user_id, {
                method: 'GET',
                mode: 'cors',
                credentials: 'include',
                headers: {
                    'Content-Type': 'application/json'
                }
            })

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