[SPARK-17702][SQL] Code generation including too many mutable states exceeds JVM size limit.

## What changes were proposed in this pull request?

Code generation including too many mutable states exceeds JVM size limit to extract values from `references` into fields in the constructor.
We should split the generated extractions in the constructor into smaller functions.

## How was this patch tested?

I added some tests to check if the generated codes for the expressions exceed or not.

Author: Takuya UESHIN <ueshin@happy-camper.st>

Closes #15275 from ueshin/issues/SPARK-17702.