feat: jump to conflict regions in the diff

[kpatenio]

Description

For large files, finding and comparing conflict regions can be tedious when scrolling through the IntelliJ 3 way diff. Although there is an option to jump from one difference to the next via the provided arrows at the top left corner of the diff window, this jump applies for all differences, and not only those relating to those that conflict. By having the option to jump from one conflicting difference to the other, we can quickly find the relevant conflict regions at the click of a button.

To implement this design, we would have to rely on IntelliJ's APIs. In the initial version of ExplainMergeConflict, there is already functionality that determines the range (lines of code) for a particular conflict region. We can use this for this particular feature.

Sample design