fix: Add missing management.setEnabled
fix: Add missing management.setEnabled

setEnabled is partially implemented in Firefox:
- https://bugzil.la/1282982
- https://developer.mozilla.org/docs/Mozilla/Add-ons/WebExtensions/API/management/setEnabled

The management API has many more methods in Chrome,
Firefox does not support them:
- createAppShortcut
- generateAppForLink
- getPermissionWarningsById
- getPermissionWarningsByManifest
- launchApp
- setLaunchType
- uninstall

brightbytes/webextension-polyfill,brightbytes/webextension-polyfill