Create indexing sticky notification that show indexing progress in all mining dashboard related pages

frontend/src/app/components/loading-indicator/loading-indicator.component.html

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+<div *ngIf="this.indexingProgress$ | async as progress" class="sticky-loading">
+  <span *ngIf="progress >= 0" class="mr-auto badge badge-pill badge-warning">Indexing blocks ({{ progress }}%)</span>
+</div>

frontend/src/app/components/loading-indicator/loading-indicator.component.scss

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+.sticky-loading {
+  position: fixed;
+  right: 10px;
+  z-index: 100;
+  @media (width > 991px) {
+    bottom: 15px;
+  }
+  @media (576px <= width <= 991px) {
+    bottom: 60px;
+  }
+  @media (width <= 575px) {
+    top: 17px;
+  }
+}

frontend/src/app/components/loading-indicator/loading-indicator.component.ts

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+import { ChangeDetectionStrategy, Component, Input, OnInit } from '@angular/core';
+import { Observable } from 'rxjs';
+import { map } from 'rxjs/operators';
+import { StateService } from 'src/app/services/state.service';
+import { WebsocketService } from 'src/app/services/websocket.service';
+
+@Component({
+  selector: 'app-loading-indicator',
+  templateUrl: './loading-indicator.component.html',
+  styleUrls: ['./loading-indicator.component.scss'],
+  changeDetection: ChangeDetectionStrategy.OnPush
+})
+export class LoadingIndicatorComponent implements OnInit {
+  @Input() name: string;
+
+  public indexingProgress$: Observable<number>;
+
+  constructor(
+    private stateService: StateService,
+    private websocketService: WebsocketService
+  ) {}
+
+  ngOnInit() {
+    this.indexingProgress$ = this.stateService.loadingIndicators$
+      .pipe(
+        map((indicators) => indicators[this.name] ?? -1)
+      );
+  }
+}