Fix DSpace#5332: Fix inconsistent rendering of <em> tag in system-wide alerts across views

(cherry picked from commit e44f9cf)

Author: guillermo-escire

src/app/system-wide-alert/alert-banner/system-wide-alert-banner.component.scss

@@ -0,0 +1,4 @@
+:host ::ng-deep .alert em {
+  font-style: italic !important;
+  font-weight: normal !important;
+}