Drag n drop sorting for custom fields (#237)

* Implement sorting for custom fields

Adds angular/cdk to sources and makes DragDropModule globally available.
Updates the add-edit component with necessary tags.
Restructures and updates the box styling for drag 'n drop handling.

* Set the correct Angular CDK version

* Remove unused class for drag handle

* Add missing locale entry for drag handle

* Fix styling of the drag handle

* Move drag handle to right side of custom fields

* Revert changes in package-lock.json

* Update reference for jslib

src/app/app.module.ts

@@ -9,6 +9,7 @@ import { InfiniteScrollModule } from 'ngx-infinite-scroll';
 import { AppRoutingModule } from './app-routing.module';
 import { ServicesModule } from './services.module';
 
+import { DragDropModule } from '@angular/cdk/drag-drop';
 import { NgModule } from '@angular/core';
 import { FormsModule } from '@angular/forms';
 import { BrowserModule } from '@angular/platform-browser';
@@ -138,6 +139,7 @@ registerLocaleData(localeZhTw, 'zh-TW');
         }),
         ToasterModule.forRoot(),
         InfiniteScrollModule,
+        DragDropModule,
     ],
     declarations: [
         AddEditComponent,