Fix room tinting
Fix room tinting

Looks like the cachebuster stuff in
https://github.com/vector-im/vector-web/pull/2515 broke room tinting. Add a
fix, along with some ranting.

matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,aperezdc/matrix-react-sdk,aperezdc/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,aperezdc/matrix-react-sdk,aperezdc/matrix-react-sdk