Mark classes of package jstasks as @Nullsafe (#42852)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/42852

All these classes are NullSafe, let's mark them as NullSafe(Local) to ensure lint detect errors in the future

changelog: [internal] internal

Reviewed By: cortinico

Differential Revision: D53393137

fbshipit-source-id: 9ed2d2b28d3ad6ecb644eeb494ac2511e3b2397e

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/jstasks/LinearCountingRetryPolicy.java

@@ -7,6 +7,9 @@
 
 package com.facebook.react.jstasks;
 
+import com.facebook.infer.annotation.Nullsafe;
+
+@Nullsafe(Nullsafe.Mode.LOCAL)
 public class LinearCountingRetryPolicy implements HeadlessJsTaskRetryPolicy {
 
   private final int mRetryAttempts;

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/jstasks/NoRetryPolicy.java

@@ -7,6 +7,9 @@
 
 package com.facebook.react.jstasks;
 
+import com.facebook.infer.annotation.Nullsafe;
+
+@Nullsafe(Nullsafe.Mode.LOCAL)
 class NoRetryPolicy implements HeadlessJsTaskRetryPolicy {
 
   public static final NoRetryPolicy INSTANCE = new NoRetryPolicy();