These imports have moved. One day importing them by the old name will
stop working. For now they just leave a warning in our logs. But better
not to have those warnings in our logs.
This commit’s parent introduces a Node-based way of managing front end assets.
Nothing else is needed in the app, specifically not Flask Assets. Flask itself
automatically routes requests for `domain.tld/static/*` to the files in
`app/static`.
This also removes all the Ruby stuff.
