Add Custom TitleView (#512)

* feat(titleView): Add Custom TitleView support

* fix: wrap TitleView in Focusable

* fix: remove root div on TitleView

frontend/src/components/TitleView.tsx

@@ -49,15 +49,15 @@ const TitleView: VFC = () => {
   }
 
   return (
-    <div className={staticClasses.Title} style={titleStyles}>
+    <Focusable className={staticClasses.Title} style={titleStyles}>
       <DialogButton
         style={{ height: '28px', width: '40px', minWidth: 0, padding: '10px 12px' }}
         onClick={closeActivePlugin}
       >
         <FaArrowLeft style={{ marginTop: '-4px', display: 'block' }} />
       </DialogButton>
-      <div style={{ flex: 0.9 }}>{activePlugin.name}</div>
-    </div>
+      {activePlugin?.titleView || <div style={{ flex: 0.9 }}>{activePlugin.name}</div>}
+    </Focusable>
   );
 };
 

frontend/src/plugin.ts

@@ -5,6 +5,7 @@ export interface Plugin {
   content?: JSX.Element;
   onDismount?(): void;
   alwaysRender?: boolean;
+  titleView?: JSX.Element;
 }
 
 export enum InstallType {