chore: Switch asyncComponent to React Lazy/Suspense (Closes #1577) (#1582)

* Attempted Lazy load for OHIFCornerStoneViewport

* Converted dicom-(html, microscopy, pdf) & cornerstone extensions to React Lazy components

* Fixed incorrect import from OHIFDicomPDFSopClassHandler to ConnectedOHIFDicomPDFViewer

Co-authored-by: Ankit Mohan <ankit.mohan@live.in>
Co-authored-by: Erik Ziegler <erik.sweed@gmail.com>

extensions/dicom-microscopy/src/asyncComponent.js

@@ -1,37 +0,0 @@
-/**
- * We use this component to leverage "Code Splitting"
- *
- * Link: https://serverless-stack.com/chapters/code-splitting-in-create-react-app.html
- */
-
-import React, { Component } from 'react';
-
-export default function asyncComponent(importComponent) {
-  class AsyncComponent extends Component {
-    constructor(props) {
-      super(props);
-
-      this.state = {
-        component: null,
-      };
-    }
-
-    async componentDidMount() {
-      // Add dynamically loaded component to state
-      const { default: component } = await importComponent();
-
-      this.setState({
-        component: component,
-      });
-    }
-
-    render() {
-      const C = this.state.component;
-
-      // Render the loaded component, or null
-      return C ? <C {...this.props} /> : null;
-    }
-  }
-
-  return AsyncComponent;
-}

extensions/dicom-microscopy/src/index.js

@@ -1,11 +1,17 @@
-import asyncComponent from './asyncComponent.js';
+import React from 'react';
 import DicomMicroscopySopClassHandler from './DicomMicroscopySopClassHandler.js';
 
-const DicomMicroscopyViewport = asyncComponent(() =>
-  import(
-    /* webpackChunkName: "DicomMicroscopyViewport" */ './DicomMicroscopyViewport.js'
-  )
-);
+const Component = React.lazy(() => {
+  return import('./DicomMicroscopyViewport');
+});
+
+const DicomMicroscopyViewport = props => {
+  return (
+    <React.Suspense fallback={<div>Loading...</div>}>
+      <Component {...props} />
+    </React.Suspense>
+  );
+};
 
 export default {
   /**