Add proxy configuration to avoid CORS restrictions

[FredrikAugust]

I got it to work with using proxies on frontend.

Steps to reproduce:

• Add to package.json:

    "proxy": "http://localhost:5000",

• Code used for testing

            <button
                onClick={() =>
                    fetch('/graphql', {
                        method: 'POST',
                        headers: { 'Content-Type': 'application/json' },
                        body: `{"operationName":null,"variables":{},"query":"{ forecast { forecastGeometry { coordinates } } } "}`,
                    })
                }
            >
                test
            </button>

Remember that when proxying you need to make a request to the host you're serving the app from. This is done by default when omitting the host in the fetch request, and only including the path.

Originally posted by @FredrikAugust in IT2901-SINTEF01/backend#29 (comment)

[blauks]

Nice, thanks for the help!:)