fix(material-experimental/mdc-paginator): add screen reader announcement for current range when navigating between pages (#23285)

(cherry picked from commit b3a6a0a)

Author: amysorto

src/material-experimental/mdc-paginator/paginator.html

@@ -27,7 +27,7 @@
     </div>
 
     <div class="mat-mdc-paginator-range-actions">
-      <div class="mat-mdc-paginator-range-label">
+      <div class="mat-mdc-paginator-range-label" aria-live="polite">
         {{_intl.getRangeLabel(pageIndex, pageSize, length)}}
       </div>