Add open graph block preview page

frontend/src/app/components/master-page-preview/master-page-preview.component.ts

@@ -0,0 +1,25 @@
+import { Component, OnInit } from '@angular/core';
+import { StateService } from '../../services/state.service';
+import { Observable, merge, of } from 'rxjs';
+import { LanguageService } from 'src/app/services/language.service';
+
+@Component({
+  selector: 'app-master-page-preview',
+  templateUrl: './master-page-preview.component.html',
+  styleUrls: ['./master-page-preview.component.scss'],
+})
+export class MasterPagePreviewComponent implements OnInit {
+  network$: Observable<string>;
+  officialMempoolSpace = this.stateService.env.OFFICIAL_MEMPOOL_SPACE;
+  urlLanguage: string;
+
+  constructor(
+    public stateService: StateService,
+    private languageService: LanguageService,
+  ) { }
+
+  ngOnInit() {
+    this.network$ = merge(of(''), this.stateService.networkChanged$);
+    this.urlLanguage = this.languageService.getLanguageForUrl();
+  }
+}