Fix formatting quirks + migrate from webpack to Rollup (#117)

The new version of `wasm-pack` does not work well with `webpack` (the current bundler), so we now take `Rollup` instead. The `wasm` module must now be loaded explicitly in `formatter/index.js`. On the side, fix some quirks of the formatter regarding CONSTRUCT and FROM.

backend/static/js/qleverUI.js

@@ -223,12 +223,8 @@ $(document).ready(function () {
 
   // Attach format funtion to formatButton.
   const formatButton = $("#formatButton");
-  formatButton.click(async function() {
-    formatter.then((formatter_fulfilled) => {
-      editor.setValue(formatter_fulfilled.format(editor.getValue()));
-    }).catch(() => {
-      console.error("Could not load formatter library");
-    });
+  formatButton.click(function() {
+    editor.setValue(format(editor.getValue()));
   })
 
   // When clicking "Execute", do the following:

backend/templates/partials/head.html

@@ -73,7 +73,10 @@
   <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
 
   <!-- WASM formatter -->
-  <script src="{% static "js/formatter/index.js" %}"></script>
+  <script type="module">
+    import { format } from "{% static '/wasm/formatter/index.js' %}";
+    window.format = format;
+  </script>
 
   <!-- Our own JavaScript code for this demo -->
   <script src="{% static "js/helper.js" %}"></script>

formatter/index.js

@@ -1,5 +1,15 @@
-import { format_raw } from "@ioannisnezis/sparql-language-server"
+import init, { format_raw } from 'sparql-language-server/sparql_language_server_web.js';
+import wasmModule from 'sparql-language-server/sparql_language_server_web_bg.wasm';
+
+console.info("Loading WebAssembly module...")
+wasmModule().then((mod) => {
+	console.info("Initializing WebAssembly module...")
+	init(mod).then(() => console.log("WebAssembly module ready!"))
+});
+
+function format(text) {
 
-export function format(text) {
 	return format_raw(text);
 }
+
+export { format }