Add methods to Set and Map which are needed for Linter

Bug: https://github.com/dart-lang/linter/issues/1307
Change-Id: Ia62aa7715509a45eb9fb0feb48c58ffee551db34
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/259506
Commit-Queue: Samuel Rawlins <srawlins@google.com>
Reviewed-by: Phil Quitslund <pquitslund@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>

pkg/analyzer/lib/src/test_utilities/mock_sdk.dart

@@ -499,8 +499,10 @@ abstract class Map<K, V> {
   void addAll(Map<K, V> other);
   Map<RK, RV> cast<RK, RV>();
   bool containsKey(Object? key);
+  bool containsValue(Object? value);
   void forEach(void action(K key, V value));
   V putIfAbsent(K key, V ifAbsent());
+  V? remove(Object? key);
 }
 
 class Null extends Object {
@@ -595,8 +597,13 @@ abstract class Set<E> implements Iterable<E> {
 
   bool add(E value);
   void addAll(Iterable<E> elements);
-  bool remove(Object? value);
+  bool containsAll(Iterable<Object?> other);
+  Set<E> difference(Set<Object?> other);
+  Set<E> intersection(Set<Object?> other);
   E? lookup(Object? object);
+  bool remove(Object? value);
+  void removeAll(Iterable<Object?> elements);
+  void retainAll(Iterable<Object?> elements);
 
   static Set<T> castFrom<S, T>(Set<S> source, {Set<R> Function<R>()? newSet}) =>
       throw '';