feat: upgrade to Angular 9 and Nebular 5 (#5628)

BREAKING CHANGE:
Angular updated to version 9.
Nebular updated to version 5.
`@agm/core` replaced with `@angular/google-maps`.
`ng2-completer` replaced with `@akveo/ng2-completer`, read details [here](https://github.com/akveo/ng2-smart-table/pull/1140#issue-392285957).

src/app/pages/maps/maps.module.ts

@@ -0,0 +1,24 @@
+import { NgModule } from '@angular/core';
+import { GoogleMapsModule } from '@angular/google-maps';
+import { LeafletModule } from '@asymmetrik/ngx-leaflet';
+import { NgxEchartsModule } from 'ngx-echarts';
+import { NbCardModule } from '@nebular/theme';
+
+import { ThemeModule } from '../../@theme/theme.module';
+import { MapsRoutingModule, routedComponents } from './maps-routing.module';
+
+@NgModule({
+  imports: [
+    ThemeModule,
+    GoogleMapsModule,
+    LeafletModule.forRoot(),
+    MapsRoutingModule,
+    NgxEchartsModule,
+    NbCardModule,
+  ],
+  exports: [],
+  declarations: [
+    ...routedComponents,
+  ],
+})
+export class MapsModule { }