[SPARK-13456][SQL][FOLLOW-UP] lazily generate the outer pointer for case class defined in REPL

## What changes were proposed in this pull request?

In https://github.com/apache/spark/pull/11410, we missed a corner case: define the inner class and use it in `Dataset` at the same time by using paste mode. For this case, the inner class and the `Dataset` are inside same line object, when we build the `Dataset`, we try to get outer pointer from line object, and it will fail because the line object is not initialized yet.

https://issues.apache.org/jira/browse/SPARK-13456?focusedCommentId=15209174&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15209174 is an example for this corner case.

This PR make the process of getting outer pointer from line object lazy, so that we can successfully build the `Dataset` and finish initializing the line object.

## How was this patch tested?

new test in repl suite.

Author: Wenchen Fan <wenchen@databricks.com>

Closes #11931 from cloud-fan/repl.