External Storage: ignore folder pattern

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Is your feature request related to a problem? Please describe.
I have mounted some other folders into NextCloud using External Storages. I use ZFS and in my case NextCloud tries to index the .zfs Folder inside a External Storage Folder. The .zfs Folder contains many snapshots (quickly changing files); 99,8% of the total files at the Moment.

Describe the solution you'd like
There should be a Option (even if its just in the config.php) to ignore folders that match specific patterns. (Also .stversions comes to mind for Syncthing, or .git, ...)

Describe alternatives you've considered

• Ignore .zfs by default (but a few people might want it indexed - even though 99% probably don't)
• Create an option in NextCloud Core to ignore file/folder patterns on the server - independent of if it is external storage or native.
• Deactivate the .zfs folder in ZFS - I will probably do this, but this is definitely a convenience downgrade for me.
• Change the folder hierarchy so that NextCloud can't view the .zfs folder.

Additional context
[None]

Start by tracing the External Storage indexing flow and reviewing how config.php options are handled. Compare the requested behavior for .zfs, .stversions, and .git, then define how configurable folder patterns should be applied and how completion can be verified without indexing matching folders.