Update manifest.json with browser-specific permissions

[maxxcrawford]

Summary

Our Chrome submission of the add-on is being rejected because we have a Firefox-specific permission listed in the manifest file: menus

Previously, this permission was ignored. It is now grounds for rejection: https://developer.chrome.com/docs/webstore/troubleshooting/#does-not-work

Jira: https://mozilla-hub.atlassian.net/browse/MPP-3466

TODO:

• [ ] ~Update Chrome release steps in internal documentation~ Won't update until this PR is merged
• [x] Update README
• [x] Update GitHub Workflows
• [x] Update NPM scripts (package.json)

Starting now, this project will only update the manifest (for Chrome) during build processes. This means without running the proper script, the add-on will not work for Chrome.

Testing

Confirm defaults work for Firefox

• Run npm run dev
• Expected it should open up Firefox (desktop) add-on locally

Confirm you can work on Chrome locally

• Run npm run web-ext-run:chrome
• Expected it should open up Chrome add-on locally

Confirm you can build the add-on locally for a targeted platform/stage environment:

[!NOTE]
You can also test by examining the output manifest.json file and confirming that Firefox builds have the menus permission while the Chrome builds have contextMenus.

For Firefox/Stage

• Run npm run build:stage
• Expected: There's an output in web-ext-artifacts for a Firefox build (Test by installing on Nightly) pointed at stage

For Chrome/Prod

• Run npm run build:chrome-prod
• Expected: There's an output in web-ext-artifacts for a Chrome build (Test by installing on Chrome) pointed at prod