Add common top-level Action type

This makes for better type inference.

src/services/bootloader.ts

@@ -1,10 +1,10 @@
 // SPDX-License-Identifier: MIT
 // Copyright (c) 2020 The Pybricks Authors
 
-import { Action, Dispatch } from 'redux';
+import { Action, Dispatch } from '../actions';
+
 import {
     BootloaderConnectionActionType,
-    BootloaderConnectionSendAction,
     didCancel,
     didConnect,
     didDisconnect,
@@ -130,11 +130,10 @@ async function send(action: Action, dispatch: Dispatch): Promise<void> {
         if (!char) {
             throw Error('Not connected');
         }
-        const sendAction = action as BootloaderConnectionSendAction;
-        if (sendAction.withResponse) {
-            await char.xWriteValueWithResponse(sendAction.data);
+        if (action.withResponse) {
+            await char.xWriteValueWithResponse(action.data);
         } else {
-            await char.xWriteValueWithoutResponse(sendAction.data);
+            await char.xWriteValueWithoutResponse(action.data);
         }
         dispatch(didSend());
     } catch (err) {

src/services/editor.ts

@@ -2,7 +2,7 @@
 // Copyright (c) 2020 The Pybricks Authors
 
 import * as FileSaver from 'file-saver';
-import { Action, Dispatch } from 'redux';
+import { Action, Dispatch } from '../actions';
 import { EditorActionType, EditorOpenAction } from '../actions/editor';
 import { RootState } from '../reducers';
 import { combineServices } from '.';

src/services/index.ts

@@ -1,7 +1,8 @@
 // SPDX-License-Identifier: MIT
 // Copyright (c) 2020 The Pybricks Authors
 
-import { Action, Dispatch, Middleware } from 'redux';
+import { Middleware } from 'redux';
+import { Action, Dispatch } from '../actions';
 import { RootState } from '../reducers';
 import bootloader from './bootloader';
 import editor from './editor';