Remove all uses of React.FC in our TypeScript code

[humphd]

What happened:

We have a mix of different approaches to defining our React components in the next.js TypeScript. In some places we use React.FC for typing, and in others we don't.

Let's remove all instances of React.FC.

What should have happened:

According to facebook/create-react-app#8177, there are some issues with always using FC, and we'd probably be better served by removing it. I also think this will be a win for new React devs who don't know TS very well, and encounter FC for the first time in our code.

If you're reviewing new code, ask the developer to remove FC. For any that slips in, let's do a sweep and remove it all later on.

See also discussion in #1531 (comment).

[HyperTHD]

Update: As of January 25th, 2021, only the Banner component uses FC. Once DynamicBannerImage is ported over and we start work on the Banner component, this will change. We can close this issue and work on #1557 after the Banner component is ported over.

[HyperTHD]

#1667 is the PR that addresses the last component using React.FC, which is the banner component. Once that's taken cared of, this issue can be closed