refs https://github.com/TryGhost/Team/issues/1217
- moved top-level `tenorApiKey` to `tenor:apiKey` and added `tenor:contentFilter`
- added base config to `defaults.json`
- updated `public-config.js` and API output serializer to use the new top-level `tenor` key
refs https://github.com/TryGhost/Team/issues/1217
- add `tenorApiKey` to `publicConfig.config()
- update canary config endpoint output serializer to include `tenorApiKey` when the `gifsCard` labs flag is enabled