Serial Plotter implementation (#597)

* spawn new window where to instantiate serial plotter app

* initialize serial monito web app

* connect serial plotter app with websocket

* use npm serial-plotter package

* refactor monitor connection and fix some connection issues

* fix clearConsole + refactor monitor connection

* add serial unit tests

* refactoring and cleaning code

arduino-ide-extension/src/node/plotter/plotter-backend-contribution.ts

@@ -0,0 +1,29 @@
+import * as express from 'express';
+import { injectable } from 'inversify';
+import { BackendApplicationContribution } from '@theia/core/lib/node/backend-application';
+import path = require('path');
+
+@injectable()
+export class PlotterBackendContribution
+  implements BackendApplicationContribution
+{
+  async initialize(): Promise<void> {}
+
+  configure(app: express.Application): void {
+    const relativePath = [
+      '..',
+      '..',
+      '..',
+      'build',
+      'arduino-serial-plotter-webapp',
+      'build',
+    ];
+    app.use(express.static(path.join(__dirname, ...relativePath)));
+    app.get('/plotter', (req, res) => {
+      console.log(
+        `Serving serial plotter on http://${req.headers.host}${req.url}`
+      );
+      res.sendFile(path.join(__dirname, ...relativePath, 'index.html'));
+    });
+  }
+}