monaco_editor: allow inclusion of external js

By using a magic comment such as

```javascript
   // erp5_monaco_editor_include: ../other.js other
```
we can tell monaco editor that other.js will be loaded before the
current javascript file, which helps the typescript compiler in
diagnosing errors and providing completions.

rsvp, renderjs and jio are still always loaded because they are used in
almost all our javscripts.

/reviewed-on nexedi/erp5!969

bt5/erp5_monaco_editor/SkinTemplateItem/portal_skins/erp5_monaco_editor/monaco_editor_support.zpt

@@ -117,6 +117,35 @@ $script.onload = function() {
     monaco.languages.html.htmlDefaults.options.format.tabSize = 2;
     monaco.languages.html.htmlDefaults.options.format.insertSpaces = true;
   }
+  if (mode === "javascript") {
+    // load an external library in namespace of the edited .js
+    function addExtraLibrary(script_name, lib_name) {
+      return fetch(script_name)
+        .then(function(resp) {
+          return resp.text();
+        })
+        .then(function(script_code) {
+          monaco.languages.typescript.javascriptDefaults.addExtraLib(
+            script_code,
+            lib_name
+          );
+        });
+    }
+    let lines = $textarea.value.split('\n');
+    // type mapping for nexedi libraries, plus external references from current document.
+    let extra_libraries = [
+        addExtraLibrary('../monaco-rsvp.d.ts', 'rsvp'),
+        addExtraLibrary('../monaco-renderjs.d.ts', 'renderjs'),
+        addExtraLibrary('../monaco-jio.d.ts', 'jio')]
+
+    for(let i = 0; i < lines.length; i++){
+      let match = lines[i].match(/erp5_monaco_editor_include\:\s*([^\s]+)\s+([a-zA-Z0-9]+)/);
+      if (match){
+        addExtraLibrary(match[1], match[2]);
+      }
+    }
+    Promise.all(extra_libraries);
+  }
   monaco.languages.registerDocumentFormattingEditProvider('javascript', {
     provideDocumentFormattingEdits(model, options, token) {
       const text = prettier.format(model.getValue(), {
@@ -149,25 +178,6 @@ $script.onload = function() {
     module: monaco.languages.typescript.ModuleKind.UMD
   });
 
-  // Type mapping for Nexedi libraries
-  function addExtraLibrary(script_name, lib_name) {
-    return fetch(script_name)
-      .then(function(resp) {
-        return resp.text();
-      })
-      .then(function(script_code) {
-        monaco.languages.typescript.javascriptDefaults.addExtraLib(
-          script_code,
-          lib_name
-        );
-      });
-  }
-  Promise.all([
-      addExtraLibrary('../monaco-rsvp.d.ts', 'rsvp'),
-      addExtraLibrary('../monaco-renderjs.d.ts', 'renderjs'),
-      addExtraLibrary('../monaco-jio.d.ts', 'jio')]);
-
-
   var timeout = null;
 
   // minimal pollyfil for AbortController