Allow to disable the online pdf viewer in Nextcloud Office

Describe the bug
Nextcloud Office is a great tool for working (collaboratively) online on writable documents.
Unfortunatly it breaks the simple download feature that Nextcloud provides for pdf files.

Without Nextcloud Office enabled Nextcloud allows users to download pdf files with a simple click on the pdf file. This is the most intuitive behaviour and the wanted behaviour in 99.999% of all cases.

Unfortunately when Nextcloud Office is enabled this simple download option gets replaced by a procedure which is

• time consuming (since Nextcloud Office takes ages to load large pdf files)
• unsafe (Nextcloud Office fails in certain cases, see #3332)
• resource intensive (consumes a lot of memory and CPU on the server side)
• unpleased (scrolling and search is complicated and takes a lot of time)
• functionless (the online pdf viewer missed a lot of features, e.g. it cannot play embedded videos or animations, ...)

Of cause there is the three dots menu where users can enforce the download. However, new or external users do typically not use this menu. That's why we need a useful default for the normal click operation or at least an configuration option to disable Nextcloud Office for certain file types.

To Reproduce
Steps to reproduce the behavior:

1. Enable Nextcloud Office
2. Click on a pdf file in the files app.
3. See how Nextcloud Office starts and tries to open or open the pdf file in an online viewer.

Expected behavior
When a user clicks on a pdf file in the files app the pdf file should always be downloaded regardless of whether Nextcloud Office is enabled or not.

Client details:

• OS: Windows, Linux, MaxOS
• Browser: Chrome, Firefox
• Device: desktop

Server details

Nextcloud version:
29.0.10

Version of the richdocuments app
8.4.9

Version of Collabora Online
24.04.2.1 80a6f97

Configuration of the richdocuments app
Not needed here.

Reproduce the behavior in the Files app with Nextcloud Office enabled and a PDF file, using the versions listed in the report. Trace how the PDF click is handled between richdocuments and the Files app, then make the normal click download PDFs or provide a configuration option to disable the online viewer for selected file types.