External Storage "local: Support read only folders

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Is your feature request related to a problem? Please describe.
I want include a local folder in to my nextcloud as External Storage. The access should be readonly. So the www-data user should only get read access to the directory. (Owner of the files is root.) That actually didn't work, because www-data needs write access to the directory (see docs).

Describe the solution you'd like
For External Storage "local" the www-data user doesn't need to have write access to the folder. The user must only have read access, if the External Storage is configured as read only.

Describe alternatives you've considered
A actual workaround is creating a SMB share and include this in to the nextcloud. This works with read only on the folder. But the down site is the accessibility from other hosts, even if a authentication is required.

Start with the linked local external storage documentation and compare its stated permissions requirements with the requested read-only behavior. Determine whether the repository should document existing support or track a product change; done means the intended behavior and required documentation or implementation scope are clearly established.