Fix: displays of CGU pop-in in small screen

Solve some scroll problems in smaller screens

src/app/shared/components/cgu-modal/cgu-modal.component.html

 <div class="modal cgu-modal" [ngClass]="{'is-active': cguModalIsOpened }">
   <div class="modal-background"></div>
-  <div class="modal-card">
+  <div class="modal-card" #cguAnchor>
     <header class="modal-card-head">
       <p class="has-text-weight-bold" i18n="@@cgu.modal.title">Terms of use</p>
       <button class="modal-close is-large" aria-label="close" (click)="closeCguModal()"></button>
@@ -21,4 +21,4 @@
       </div>
     </footer>
   </div>
-</div>
\ No newline at end of file
+</div>

src/app/shared/components/cgu-modal/cgu-modal.component.ts

-import { Component, EventEmitter, OnInit, Output } from '@angular/core';
+import { Component, EventEmitter, OnInit, Output, ViewChild, ElementRef } from '@angular/core';
 import { DomSanitizer, SafeHtml } from '@angular/platform-browser';
 import { ActivatedRoute, Router } from '@angular/router';
 import { CookieService } from 'ngx-cookie-service';
@@ -22,6 +22,7 @@ export class CguModalComponent implements OnInit {
   shakeAnimation = false;
 
   @Output() cguAccepted = new EventEmitter();
+  @ViewChild('cguAnchor', {static:true}) cguAnchor: ElementRef;
 
   constructor(
     private _editorialisationService: EditorialisationService,
@@ -77,9 +78,15 @@ export class CguModalComponent implements OnInit {
   }
 
   modalBodyScrolled(event) {
+
     const target = event.target || event.srcElement;
     if (Math.ceil(target.scrollTop) + target.offsetHeight >= target.scrollHeight) {
       this.isCguScrolledEntirely = true;
     }
+    else {
+      this.cguAnchor.nativeElement.scrollIntoView({ behavior: "smooth", block: "start", inline:'nearest' });
+      const y = this.cguAnchor.nativeElement.getBoundingClientRect().top + window.pageYOffset -80;
+      window.scrollTo({top: y, behavior: 'smooth'});
+    }
   }
 }