move vue and vue-calendar-heatmap to webpack (#10188)

- unvendor vue and vue-calendar-heatmap
- remove unused moment.js leftover from previous heatmap version
- ensure webpack loads the full version of vue
- fix vue devmode warning related to 'searchLimit' type

I wanted to name the chunk heatmap.js but adblockers don't like that
filename [1].

[1] 3899d5dff3/easyprivacy/easyprivacy_general.txt (L2095)

.eslintrc

@@ -23,7 +23,6 @@ globals:
   emojify: false
   SimpleMDE: false
   u2fApi: false
-  Vue: false
 
 rules:
   arrow-body-style: [0]