added styling so layer upgrade pagination buttons are visible in dark mode (#680)

Author: erinehall

nav-app/src/app/layer-upgrade/layer-upgrade.component.scss

@@ -54,6 +54,10 @@ h4 {
     min-height: unset;
 }
 
+.mat-mdc-paginator .mat-mdc-paginator-icon {
+    @include adaptive-color-dark-only('fill', on-color(dark))
+}
+
 .mat-stepper-vertical,
 .mat-mdc-paginator {
     @include adaptive-color-dark-only('background-color', color(dark-3));