[HUDI-2432] Adding restore.requested instant and restore plan for restore action (#4605)

- This adds a restore plan and serializes it to restore.requested meta file in timeline. This also means that we are introducing schedule and execution phases for restore which was not present before.

hudi-client/hudi-spark-client/src/test/java/org/apache/hudi/client/functional/TestHoodieClientOnCopyOnWriteStorage.java

@@ -576,6 +576,7 @@ public class TestHoodieClientOnCopyOnWriteStorage extends HoodieClientTestBase {
     HoodieWriteConfig newConfig = getConfigBuilder().withProps(config.getProps()).withTimelineLayoutVersion(
         TimelineLayoutVersion.CURR_VERSION).build();
     client = getHoodieWriteClient(newConfig);
+
     client.restoreToInstant("004");
 
     assertFalse(metaClient.reloadActiveTimeline().getRollbackTimeline().lastInstant().isPresent());