pybricksMicropython/lib: add module

This creates a new module for dealing with stuff specific to Pybricks
MicroPython.

src/editor/OpenButton.tsx

@@ -4,6 +4,7 @@
 import React, { useContext } from 'react';
 import { useDispatch } from 'react-redux';
 import * as notificationActions from '../notifications/actions';
+import { pythonFileExtension } from '../pybricksMicropython/lib';
 import OpenFileButton, { OpenFileButtonProps } from '../toolbar/OpenFileButton';
 import { TooltipId } from '../toolbar/i18n';
 import { EditorContext } from './Editor';
@@ -18,7 +19,7 @@ const OpenButton: React.FunctionComponent<OpenButtonProps> = (props) => {
 
     return (
         <OpenFileButton
-            fileExtension=".py"
+            fileExtension={pythonFileExtension}
             tooltip={TooltipId.Open}
             icon={openIcon}
             enabled={editor !== null}

src/editor/sagas.ts

@@ -3,6 +3,7 @@
 
 import FileSaver from 'file-saver';
 import { call, getContext, put, takeEvery } from 'typed-redux-saga/macro';
+import { pythonFileExtension, pythonFileMimeType } from '../pybricksMicropython/lib';
 import { ensureError } from '../utils';
 import { EditorType } from './Editor';
 import { didFailToSaveAs, didSaveAs, open, saveAs } from './actions';
@@ -37,7 +38,7 @@ function* handleSaveAs(): Generator {
     }
 
     const data = editor.getValue();
-    const blob = new Blob([data], { type: 'text/x-python;charset=utf-8' });
+    const blob = new Blob([data], { type: `${pythonFileMimeType};charset=utf-8` });
 
     if (window.showSaveFilePicker) {
         // This uses https://wicg.github.io/file-system-access which is not
@@ -48,7 +49,7 @@ function* handleSaveAs(): Generator {
                     suggestedName: 'main.py',
                     types: [
                         {
-                            accept: { 'text/x-python': '.py' },
+                            accept: { [pythonFileMimeType]: pythonFileExtension },
                             // TODO: translate description
                             description: 'Python Files',
                         },