Fix selection after running a settings quick action

The settings quick actions (the buttons on the global/org/user settings JSON editor pages) yield the wrong selection after clicking them in some cases. The selection should be the newly added line, but it instead is the line above.

This only occurs for actions (such as setSearchContextLines) that DO NOT specify a selection text.

This is because the selection is computed as:

                    selection = monaco.Selection.fromPositions(
                        monacoEdits[0].range.getStartPosition(),
                        monacoEdits[monacoEdits.length - 1].range.getEndPosition()
                    )

and this breaks when the edit needs to add a trailing comma to the preceding line.