[SPARK-12981] [SQL] extract Pyhton UDF in physical plan

[davies]

What changes were proposed in this pull request?

Currently we extract Python UDFs into a special logical plan EvaluatePython in analyzer, But EvaluatePython is not part of catalyst, many rules have no knowledge of it , which will break many things (for example, filter push down or column pruning).

We should treat Python UDFs as normal expressions, until we want to evaluate in physical plan, we could extract them in end of optimizer, or physical plan.

This PR extract Python UDFs in physical plan.

Closes #10935

How was this patch tested?

Added regression tests.

[davies]

cc @marmbrus

[SparkQA]

Test build #54765 has finished for PR 12127 at commit c10d80d.

• This patch fails Scala style tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #54766 has finished for PR 12127 at commit cf97922.

• This patch fails Spark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #2732 has finished for PR 12127 at commit cf97922.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[marmbrus]

LGTM

[davies]

Merging this into master, thanks!