ui: monaco: upgrade to 0.57, drop monaco-editor-webpack-plugin

- Migrate entry points to the 0.57 exports scheme (monaco-editor/editor,
  languages/features/typescript/register)
- Wire workers via the official MonacoEnvironment.getWorker +
  new Worker(new URL(...)) integration; webpack emits them as shared-chunk
  classic workers (chrome 70 compatible), total assets -21%
- Keep css/html/json language features (register.all) and route their
  worker labels; json is used by the cmeditor textareas
- Replace removed esm/vs/nls.messages with an inline implementation in the
  nls shim
- Drop MinChunkSizePlugin: it merged worker chunks into the main chunk and
  broke the runtime id module (webpack#15416)
- Remove monaco-editor-webpack-plugin dependency
- loadMonaco() now returns the loaded feature module exports, e.g.
  loadMonaco(['typescript']).typescript.javascriptDefaults

packages/ui-default/components/scratchpad/ScratchpadEditorContainer.tsx

@@ -1,4 +1,4 @@
-import type * as monaco from 'monaco-editor';
+import type * as monaco from 'monaco-editor/editor';
 import React from 'react';
 import { connect } from 'react-redux';
 import { load } from 'vj/components/monaco/loader';