Allow specifying/importing global ignored file extension list via URL or TXT File

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### Feature description
Currently, [the ransomware-protection Nextcloud App](https://github.com/nextcloud/ransomware_protection) has been unmaintained for a few years. It provided a server-side regex-filter on the name/extension of Files to be uploaded and was advertised as preventing automatic upload of ransomware-infected files to your Nextcloud instance. Now you may think of that what you want and there is a reason this app is no longer maintained, but a simpler "ignore the following file names"-Feature is also available in the Nextcloud Desktop app.

Now, after explaining all this, what do I want? The current Nextcloud Desktop App allows manually specifying individual regex-filters which files should be ignored, however mass-import from a textfile (like [the one used in the old ransomware-protection app](https://github.com/nextcloud/ransomware_protection/blob/master/resources/extensions.txt)) or even the use of a remote list by specifying a URL instead of a regex-filter is currently not possible.

Optimal would be if the Nextcloud Server already provided a global Admin Setting that all connected Nextcloud Apps would use. Allowing the user to import a textfile containing predefined filters in the Nextcloud Desktop App would be nice, being able to specify a URL to import once (or repeatedly) from would be even better.

I can imagine this isn't a top priority topic or even widely requested, but I would assume Enterprise Customers would like to be able to control these client-side regex-filters from a central location / from the Nextcloud Admin Settings.