Add option to overwrite in export to PDF dialog

Is your feature request related to a problem? Please describe.
When I export a document (typically would be odt to pdf), and the document already exists, an increasing integer number is added as suffix to the exported document name.

Describe the solution you'd like
When I export a document (typically would be odt to pdf), I'd like to be offered the option to overwrite the document if it already exists.

Describe alternatives you've considered
Delete the existing document before re-exporting.

Additional context
Multiple copies of the same file makes the working environment harder to work with. If I delete the existing document, I need to go to trash if I have to recover it. Nextcloud has a good versioning system that elegantly solves the situation in which I need to restore a previous version of the file that makes useless the rename action that happens now.

I'm not sure however, if this request belongs here or it is best to move it in the Collabora Online repo.

Start by locating the export-to-PDF dialog in this repository and determine whether the requested behavior belongs in richdocuments or Collabora Online. Trace how an existing destination is renamed, then define completion as offering overwrite when the exported document already exists without creating a suffixed copy.