[enhancement]: [UI/UX] Diff / reused `text blocks` highlight for prompt / info

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Contact Details

_No response_

### What should this feature add?

During experiments, most of the time most of the prompt stays mostly the same. But it takes quite a time to spot the difference with a naked eye.

It would be nice to highlight entire reused blocks with color-coding. The sources for blocks detection are:
- images in gallery;
- entire generation history.

This feature request is tightly connected with:
- #2379

_(and they both would immensely benefit from each other)_

### Further enhancements
- Blocks which are present in both windows but moved to another part of prompt might be marked in some way (e.g., outlined with grey)
- If there is some popular combination of blocks, they might get the same color _(however, I'm not sure how hard it would be to track not just popular blocks but also organize them into clusters in HSV color space)_
- Spots where one prompt has missing part of text (the vertical line in mockups I've attached) might be interactive: display the missing text in popup on hover.
- As a later feature iteration, these blocks might be used to implement an auto-complete suggestion feature.

### Alternatives

_No response_

### Aditional Content