feat(v3): add callback for setData

packages/uni-mp-weixin/dist/mp.js

@@ -538,6 +538,7 @@ function initState (vm) {
       }
     });
     vm.$forceUpdate();
+    isFn(callback) && vm.$nextTick(callback);
   };
 
   initProperties(vm, instanceData);

src/core/runtime/mp/polyfill/state/index.js

 import {
+  isFn,
   hasOwn,
   isPlainObject
 } from 'uni-shared'
@@ -46,6 +47,7 @@ export function initState (vm) {
       }
     })
     vm.$forceUpdate()
+    isFn(callback) && vm.$nextTick(callback)
   }
 
   initProperties(vm, instanceData)