Info Tips: Support `thumbnail:` variants e.g. `thumbnailtext:` as fallback style

(I've written about this general subject before, but I don't think I'm covering old ground.)

It would be useful if there were Info Tip thumbnail: variants thumbnailtext: and thumbnailimage: (potentially others).

Then I could use {name}{thumbnail:1:128}{thumbnailtext:1:192}{thumbnailimage:1:512} in the "All files" group's Info Tip, and based upon what Opus recognises the file as (assuming it doesn't match a File Type Group), display only the thumbnail rule which matches, or if no text/image match, the specified generic of {thumbnail:1:96}. These variants wouldn't be useful for the user-defined file type groups since those are based upon file extensions.

The reason for this FR is because I'd like to style all of my Info Tips which produce a text preview thumbnail (.txt, LICENSE, .gitignore, etc) the same size: It seems 192px is what produces a nice and undistorted upscaled text preview thumbnail (default is 96px), but this size of thumbnail as "All files"'s default is a bit too large for me in general, so having the variant {thumbnailtext:1:192} would solve this I think. That, in combination with defining {thumbnail:1:192} (or {thumbnailtext:1:192}, same thing in this case) for my own groups, e.g. Text, Source, and Configs. With this setup, any text-based file whose extension I have not defined as text, source code, or a config, will at least show the same thumbnail size due to matching on "Any file"'s {thumbnailtext:1:192} definition.

This might be also be helpful for images (maybe videos too?): Any image I have not have specified in the Images group (thumbnails set to be 512px) will use "Any files"'s definition containing {thumbnailimage:1:512} (assuming it doesn't match on "Recognized images").

My current solution is to just accept using a bit oversized thumbnails for "All files" just so that I don't see any poorly rendered text preview thumbnails.



My initial idea was for the program to instead provide additional "Directory Opus File Types". We have "Recognized images", but what about "Recognized plaintext files" too? Opus recognises the content of LICENSE (no file ext) as text and knows to display it as a text preview thumbnail, so any files like that which don't match another group would use "Recognized plaintext files"'s definition. Then I would still have to duplicate the definition into my Text, Source, Configs groups to make sure all text files display the same size thumbnail. Maybe instead of duplicating definitions we could link one File Type Group to another, e.g. Source would use Text's definition? Not sure if this approach is better than the idea outlined above. It's all a bit hard to make sense of.

We can't easily do that without affecting other thumbnails as well (icons and folders in particular), since the thumbnail system doesn't know what's a text file and what's not. (Text thumbs do have a flag on them that most thumbnails don't, but it's also on icons and folders.)

But is it really needed to override the size of thumbnails for All Files? Overriding it for just images and videos would avoid the issue entirely, and text thumbs will look correct as long as their size isn't being overridden.