feat: angular 7+ update (#1910)

Closes #1890

BREAKING CHANGES:
Angular 7+ now required.
The following libraries were updated:
- @agm/core
- @ng-bootstrap/ng-bootstrap
- @swimlane/ngx-charts
- ng2-ckeditor
- ngx-echarts

src/app/pages/dashboard/dashboard.component.ts

@@ -1,6 +1,6 @@
 import {Component, OnDestroy} from '@angular/core';
 import { NbThemeService } from '@nebular/theme';
-import { takeWhile } from 'rxjs/operators/takeWhile' ;
+import { takeWhile } from 'rxjs/operators' ;
 
 interface CardSettings {
   title: string;

src/app/pages/dashboard/temperature/temperature-dragger/temperature-dragger.component.ts

@@ -22,7 +22,7 @@ export class TemperatureDraggerComponent implements AfterViewInit, OnChanges {
   @Input() maxLeap = 0.4;
 
   value = 50;
-  @Output('valueChange') valueChange = new EventEmitter<Number>();
+  @Output() valueChange = new EventEmitter<Number>();
   @Input('value') set setValue(value) {
     this.value = value;
   }