fix: nativescript-vue-devtools can't detect vuex

According to nativescript-vue/nativescript-vue-devtools#2 import `vuex` statement should be under `nativescript-vue-devtools` and It is true. I tested in my own.

template/app/main.ts

@@ -1,6 +1,5 @@
 import Vue from 'nativescript-vue';
 import App from './components/App.vue';
-{{#store}}import store from './store';{{/store}}
 
 {{#devtools}}import VueDevtools from 'nativescript-vue-devtools';
 
@@ -9,6 +8,8 @@ if(TNS_ENV !== 'production') {
 }
 {{/devtools}}
 
+{{#store}}import store from './store';{{/store}}
+
 // Prints Vue logs when --env.production is *NOT* set while building
 Vue.config.silent = (TNS_ENV === 'production');