feat(material/table): accept undefined sort and paginator

Extend types of the sort and paginator setter to include undefined to avoid `?? null` when using
singals (e.g. `viewChild`).

Author: rslawik

src/material/table/table-data-source.ts

@@ -107,8 +107,8 @@ export class MatTableDataSource<T, P extends MatPaginator = MatPaginator> extend
     return this._sort;
   }
 
-  set sort(sort: MatSort | null) {
-    this._sort = sort;
+  set sort(sort: MatSort | null | undefined) {
+    this._sort = sort ?? null;
     this._updateChangeSubscription();
   }
 
@@ -128,8 +128,8 @@ export class MatTableDataSource<T, P extends MatPaginator = MatPaginator> extend
     return this._paginator;
   }
 
-  set paginator(paginator: P | null) {
-    this._paginator = paginator;
+  set paginator(paginator: P | null | undefined) {
+    this._paginator = paginator ?? null;
     this._updateChangeSubscription();
   }