add a filesize overview Widget to nextcloud/dashboard

[Mannshoch]

Please add a dashboard plugin to get a Windirstat or jdiskreport like overview.

It would be nice to modifier this statistic to show most transferred data on the same directory based overview instead.

For reference: https://github.com/nextcloud/dashboard/issues/39#issuecomment-552865317

[Mannshoch]

New Dashboard Project: https://github.com/nextcloud/server/issues/20930

[joshtrichards]

Hi @Mannshoch - Thanks for your idea. Closing in favor of #226 so that expressions of interest and discussion can be centralized under one issue.