Fix/prev next links issue (#10523)

* intital test code

* added tests

* remove commented code

* fix for failing tests

* reuse exported enum

* changes to address comments

* add back onVisibility highlight

* port highlight fix from Chris

* fix tests

src/sql/workbench/contrib/notebook/browser/cellViews/linkHandler.directive.ts

@@ -4,7 +4,6 @@
  *--------------------------------------------------------------------------------------------*/
 
 import { Directive, Inject, HostListener, Input } from '@angular/core';
-
 import { URI } from 'vs/base/common/uri';
 import { IOpenerService } from 'vs/platform/opener/common/opener';
 import { onUnexpectedError } from 'vs/base/common/errors';