Ability to choose image preview size

[enjeck]

At the moment when you create a link to an image saved inside Nextcloud Files, Tables creates a very small preview image of that file (actually, this worked some time ago, has been gone and now should work again when #1393 is accepted).

Looking at the code I think this value at the moment is hardcoded to 25x25px.
My idea would be to let the user choose how big this preview should be. This would give us the chance to use Tables for example for:

some sort of inventory with a preview of the item (workshop tools, borrowed things)
create a todo list where people can add a picture of something to do (for example a photo of a defective asset)
a list of members of a club with their photo beside
Although it would be even greater to be able to upload new images directly from the input form (like already requested in the "additional columns" discussion) I would expect that having bigger previews of linked images would already be an enhancement.

As I'm new to this I asked myself if enhancing Tables to let the user choose the preview size would be very difficult?

Some of the points that would be needed and that came into my mind are:

Some kind of preference dialog where a user could set the preview size of the images. Maybe this should be settable for every table because the users sometimes would need bigger images in one table and just small ones in an other.
The possibility to save this preference inside the database beside the other values like name of the table.
Remove (or adapt) the preview link that at the moment is saved to the database when an image is linked in a column: at the moment every link inside thumbnailUrl is saved with an url like index.php/core/preview?fileId=123456&x=32&y=32 and therefore when setting Tables to show a bigger preview should use an other preview format (like x=128&y128).