Add revisions dialog (#485)

* Add mock files

Note that revisions-list needs to be called revisions in the reality to be confirm with the API spec, but our mocking solution doesn't allow that...

* Add revisions API calls

* Fix line endings in mock files

* Extend CommonModal to accept size and additionalClasses

* Clarify variable name in API request

* Add react-diff-viewer as dependency

* Add revision chooser modal

* Fix type of route params

* Added and updated mock files

* Added user-icon list per revision

* Added translation to alt text of avatars

* Updated mock file to remove inconsistencies

* Add caching for revisions

* Sort mock file revisions-list descending by timestamp

* Pre-select first/newest revision on first modal open

* Regenerated yarn.lock file from scratch

* Applied requested changes in variable names and line lengths

* User UserAvatar component instead of manually set image

* Move revision-modal-list-entry to own component

* Removed unnecessary return statements

src/components/editor/editor.tsx

@@ -113,7 +113,7 @@ export const Editor: React.FC = () => {
       <DocumentTitle title={documentTitle}/>
       <div className={'d-flex flex-column vh-100'}>
         <AppBar/>
-        <DocumentBar title={documentTitle}/>
+        <DocumentBar title={documentTitle} noteContent={markdownContent}/>
         <Splitter
           showLeft={editorMode === EditorMode.EDITOR || editorMode === EditorMode.BOTH}
           left={