[SPARK-6586][SQL] Add the capability of retrieving original logical plan of DataFrame

[viirya]

In order to solve a bug, since #5217, DataFrame now uses analyzed plan instead of logical plan. However, by doing that we can't know the logical plan of a DataFrame. But it might be still useful and important to retrieve the original logical plan in some use cases.

In this pr, we introduce the capability of retrieving original logical plan of DataFrame.

The approach is that we add an analyzed variable to LogicalPlan. Once Analyzer finishes analysis, it sets analyzed of LogicalPlan as true. In QueryExecution, we keep the original logical plan in the analyzed plan. In LogicalPlan, a method originalPlan is added to recursively replace the analyzed logical plan with original logical plan and retrieve it.

Besides the capability of retrieving original logical plan, this modification also can avoid do plan analysis if it is already analyzed.

[SparkQA]

Test build #29348 has finished for PR 5241 at commit ee1d790.

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

[viirya]

Currently the option on jira is we don't need this capability to retrieve original plan for an analyzed plan. So I close this.