feat: add view entity to entity mapping (#613)

- adds entity to entity mapping list
- displays the data as per user selection

Fixes: #485

src/app/system/entity-to-entity-mapping/entity-to-entity-mapping.resolver.ts

@@ -0,0 +1,30 @@
+/** Angular Imports */
+import { Injectable } from '@angular/core';
+import { Resolve } from '@angular/router';
+
+/** rxjs Imports */
+import { Observable } from 'rxjs';
+
+/** Custom Services */
+import { SystemService } from '../system.service';
+
+/**
+ * Entity to entity mapping data resolver.
+ */
+@Injectable()
+export class EntityToEntityMappingResolver implements Resolve<Object> {
+
+    /**
+     * @param {SystemService} systemService System service.
+     */
+    constructor(private systemService: SystemService) { }
+
+    /**
+     * Returns the Mapping data.
+     * @returns {Observable<any>}
+     */
+    resolve(): Observable<any> {
+        return this.systemService.getEntityMappings();
+    }
+
+}