[398361] Enhanced Model Merge UI - Add new Ruler next to StructureMergeViewer - When select diff in StructureMergeViewer, highlight required and unmergeable diffs, and create annotations in Ruler - Add new merge and navigation actions in StructureMergeViewer toolbar. - Delete old merge and navigation actions in ContentMergeViewer toolbar. Bug: 398361 Change-Id: I3d43fe9c4938404361f835e93631ed744a2c4377