Automate Firefox/Chrome release process

[HugoDF]

This seems to have a script to release to Firefox/Chrome: https://github.com/single-spa/single-spa-inspector#publishing-a-new-version

Uses https://www.npmjs.com/package/@wext/shipit under the hood. That package brings in a lot of dependencies, we might be better off lifting and shifting https://github.com/LinusU/wext-shipit/blob/master/lib/chrome.js and https://github.com/LinusU/wext-shipit/blob/master/lib/firefox.js

Would be ideal to have an action that:

• runs on tag
• updates package.json version to tag
• rebuilds (updates manifest.json)
• shipit's to Firefox/Chrome

Notes:

• we'll need to add the API client ids/keys as GitHub action secrets.
• Firefox extension id is {9abd6c79-c126-42cc-bacc-658d531864f1}

Resources:

• https://developer.chrome.com/webstore/using_webstore_api (to get the Chrome API tokens)

Potential alternatives:

• use GitHub Actions version of the above, see https://github.com/kewisch/action-web-ext (web-ext wrapper, for Firefox), https://github.com/marketplace/actions/chrome-extension-publish-action or https://github.com/trmcnvn/chrome-addon (publish to Chrome web store), https://github.com/trmcnvn/firefox-addon