Gatsby and Netlify setup

[r-czajkowski]

Ref: #20 #17

Add initial config to run the Threshold website with Gatsby. It also adds Netlify CMS support. The CMS admin panel is available under <domain>/admin and uses GitHub auth to login to the CMS.

Screenshots

**CMS panel**   

[github-actions[bot]]

Preview uploaded to https://preview.threshold.network/gatsby/index.html.

[github-actions[bot]]

Preview uploaded to https://preview.threshold.network/gatsby/index.html.

[georgeweiler]

Hey @r-czajkowski Amazing work! After chatting with Liz and Chris, I think the markdown dangerouslySetHTML pattern that you've chosen will work.

Here are some change requests before we merge. Let me know what you think:

• src/pages should become src/content
• /templates should be updated to allow for sub directories see: https://github.com/threshold-network/splash-page/pull/15/files#r834631633
• src/nav-bar seems out of place. Could we place our component content under the new src/content directory? Maybe we can do src/content/pages/* and src/content/components or something like that?
• we have 3 separate static directories: /static, src/static, and public/static. I'm a little confused at the difference. maybe there is some clean up we can do here?

Additional comments that we discussed (but let's figure out in a future PR)

• where possible, we should try to keep our enums instead of letting CMS users inject any info they want (select widget)
• ☝️ we should find a way for CMS users to update enums in 1 place
• styling concerns with allowing markdown. let's look in to setting up the MDX provider to inject chakra component styling

[r-czajkowski]

we have 3 separate static directories: /static, src/static, and public/static. I'm a little confused at the difference. maybe there is some clean up we can do here?

The public is a build dir of the gatsby app and we don't include public dir in the git repo so there's nothing we can do here.

The src/static is for React and you can use this file in the React scope- eg. you can import the SVG file in your React component like:

import Threshold from "../../static/images/ThresholdBrandFullWhite.svg"

<Threshold />

The static/images is for cms and all images uploaded via cms go to this directory.

@georgeweiler I've updated the dir structure please see c2b6809 9bceef8. The rest bullets we can address in further work. I think we have a minimal gatsby + cms set up so we are able to build new features with Gatsby and Netlify cms.