Add lazy loading and decoding to images (#591)

The lazy loading will work in addition to any already being done, rather
than conflicting with it.

Co-authored-by: Daniel James Smith <djsmith@web.de>

angular/src/components/icon.component.html

@@ -1,4 +1,11 @@
 <div class="icon" aria-hidden="true">
-  <img [src]="image" appFallbackSrc="{{ fallbackImage }}" *ngIf="imageEnabled && image" alt="" />
+  <img
+    [src]="image"
+    appFallbackSrc="{{ fallbackImage }}"
+    *ngIf="imageEnabled && image"
+    alt=""
+    decoding="async"
+    loading="lazy"
+  />
   <i class="bwi bwi-fw bwi-lg {{ icon }}" *ngIf="!imageEnabled || !image"></i>
 </div>