use stored API key when loading epivis 'shared' links

[melange396]

for #95

[melange396]

to test:

• visit https://deploy-preview-107--cmu-delphi-epivis.netlify.app/
• save your API key there
• close that browser window
• open a new browser window, and within it, open the network activity tab of the debugger
• paste this url into the address bar and hit enter: https://deploy-preview-107--cmu-delphi-epivis.netlify.app/#eyJjaGFydCI6eyJ2aWV3cG9ydCI6WzczNzQ1NC41LC0yLjE4MDU4MjE2NjY2NjY2NjUsNzM4OTI5LjUsMTUuMzc4MzYzMTY2NjY2NjY2XSwic2hvd1BvaW50cyI6ZmFsc2V9LCJkYXRhc2V0cyI6W3siY29sb3IiOiIjN2FjMjk1IiwidGl0bGUiOiJ2YWx1ZSIsInBhcmFtcyI6eyJfZW5kcG9pbnQiOiJjb3ZpZGNhc3QiLCJkYXRhX3NvdXJjZSI6ImNobmciLCJzaWduYWwiOiJzbW9vdGhlZF9vdXRwYXRpZW50X2NsaSIsInRpbWVfdHlwZSI6ImRheSIsImdlb190eXBlIjoibmF0aW9uIiwiZ2VvX3ZhbHVlIjoidXMifX1dfQ==
• in the debugger, notice that the request to the covidcast endpoint of api.delphi.cmu.edu includes your api key!
• for extra fun, reload the page >60 times in a short period to verify you are not affected by keyless rate limiting

[dmytrotsko]

👍