Try to get the `.editorconfig` and `.prettierrc` files as close as possible
to the formatting that was used in Flamenco. Because these files weren't
here during most of Flamenco's development so far, having them caused quite
a few changes in the webapp files.
No functional changes intended.
The support is still fairly minimal. Clusters cannot be managed via the
webapp yet, so the API has to be used directly for that. Workers can be
assigned to clusters via the webapp though.