Allow customizing link preview height

[TerjeTM]

I find the link preview useful, but unfortunately these previews are always much too small.
I would like to be able to define the height of the window to be displayed myself.
The width is okay, because when you set it to full width, it is nice and wide so that you can see the document in its entirety.

too small:

You could insert a field here where you can define the height in pixels.

Thank you!

[max-nextcloud]

I'll move this over to the text app as that's where this would need to be implemented. Will also adjust the description slightly.

[max-nextcloud]

My gut feeling is that a drag handle to adjust the size would be nice. (Like github has it for the comment entry):

My understanding is that while persisting the change would be nice being able to change the size a single time would already be a starting point. Maybe we can store the new height inside the link syntax.

[mejo-]

The discussions in #4556 are also relevant. Tiptap already brings a resizeable node view, but I'm unsure whether we can use it in combination with our custom node view Vue components.

Regarding possibilities to persist the custom size in Markdown, see this comment.

[alimmroth]

I would appreciate a sizable preview very much! 🙏 I think the current view doesn't add any value when using it.

[mejo-]

Given that we get so much feedback on this problem I wonder how to best tackle it.

I agree with @max-nextcloud that we should make it possible to resize the preview height during the editing session as a first step, with the possibility to persist the height in Markdown as a possible follow-up.

I also think that we don't want the resize handle to be available on all previews, just on the ones that show the actual content of the embedded file. For website previews and e.g. collective page or deck card previews, it would be confusing to be able to resize them.

So I guess the proper way to implement this would be a resizeable flag for custom reference provider widgets that defines whether the resize drag handle is exposed or not. What do others think?