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.component.spec.ts

@@ -0,0 +1,25 @@
+import { async, ComponentFixture, TestBed } from '@angular/core/testing';
+
+import { EntityToEntityMappingComponent } from './entity-to-entity-mapping.component';
+
+describe('EntityToEntityMappingComponent', () => {
+  let component: EntityToEntityMappingComponent;
+  let fixture: ComponentFixture<EntityToEntityMappingComponent>;
+
+  beforeEach(async(() => {
+    TestBed.configureTestingModule({
+      declarations: [ EntityToEntityMappingComponent ]
+    })
+    .compileComponents();
+  }));
+
+  beforeEach(() => {
+    fixture = TestBed.createComponent(EntityToEntityMappingComponent);
+    component = fixture.componentInstance;
+    fixture.detectChanges();
+  });
+
+  it('should create', () => {
+    expect(component).toBeTruthy();
+  });
+});