feat(app): add uni.getChannelManager()

lib/apis.js

@@ -286,7 +286,8 @@ const plugin = [
   'getPushClientId',
   'onPushMessage',
   'offPushMessage',
-  'createPushMessage'
+  'createPushMessage',
+  'getChannelManager'
 ]
 
 const apis = [

src/platforms/app-plus/service/api/plugin/push.js

@@ -82,3 +82,9 @@ export function createPushMessage (params, callbackId) {
     errMsg: 'createPushMessage:ok'
   })
 }
+
+let channelManager
+
+export function getChannelManager () {
+  return channelManager || (channelManager = plus.push.getChannelManager())
+}