common_passwords: Introduce automatic updates

Currently, this package relies on two static files deployed with the package. The content of these files is never changed, unless a new version of the package is released (and the files themselves updated manually in the source code repository). It means that the tool uses really old data.

My idea is that these files (or one file - with the data merged) will be downloaded periodically, e.g. once a week or a month. It will require the server part to be implemented too (the files would be published daily on view.sentinel.turris.cz etc.).