feat: payment modal

frontend/src/app/feature/deposit/deposit.component.html

@@ -0,0 +1,20 @@
+<h2 mat-dialog-title>Guthaben aufladen</h2>
+<mat-dialog-content>
+    <form [formGroup]="form">
+        <div *ngIf="errorMsg">
+            {{ errorMsg }}
+        </div>
+        <div>
+            <label for="amount">Betrag</label>
+            <input
+                    type="number"
+                    id="amount"
+                    formControlName="amount"
+            />
+        </div>
+    </form>
+</mat-dialog-content>
+<mat-dialog-actions>
+    <button (click)="closeDialog()">Abbrechen</button>
+    <button (click)="submit()">Einzahlen</button>
+</mat-dialog-actions>