Use morphdom to reduce number of full page updates to md preview

This should help improve scroll sync and also reduce the number of times we go out to the network if images are in the preview

extensions/markdown-language-features/preview-src/tsconfig.json

@@ -3,6 +3,7 @@
 	"compilerOptions": {
 		"outDir": "./dist/",
 		"jsx": "react",
+		"esModuleInterop": true,
 		"lib": [
 			"es2018",
 			"DOM",