Add a diff-like color highlighting to agent merging

[maxpatiiuk]

In some cases, the difference between records is hard to notice. See examples of 3 different values:

Having the differing part of text be highlighted in red/green (like in https://www.diffchecker.com/ or any other diff tool) would be helpful.

Perhaps that should only be enabled if the strings are >80% the same (so as not to spam the screen with colors when strings are obviously different)

Using any of the available diff libraries should do (though there is a difficulty of doing a diff when more than 2 records are being merged)