Update demos to use import assertions

Author: dandclark

demo1/cssModuleElement.js

@@ -1,4 +1,4 @@
-import sheet from "./styles.css";
+import sheet from "./styles.css" assert { type: "css" };
 
 class CSSModuleTestElement extends HTMLElement {
     constructor() {

demo2/cssModuleCatElement.js

@@ -1,4 +1,4 @@
-import sheet from "./big_styles.css";
+import sheet from "./big_styles.css" assert { type: "css" };
 
 class CSSModuleCatElement extends HTMLElement {
     constructor() {

demo3/cssModuleElement.js

@@ -1,4 +1,4 @@
-import sheet from "./styles.css";
+import sheet from "./styles.css" assert { type: "css" };
 
 class CSSModuleTestElement extends HTMLElement {
     constructor() {

demo4/module.html

@@ -15,7 +15,7 @@
             }
         </script>
         <script type="module">
-            import jsonData from "./citylots_reduced.json";
+            import jsonData from "./citylots_reduced.json" assert { type: "json" };
             logPerf(`Got JSON with array of length ${jsonData.features.length} items`);
         </script>
     </head>