Fix "no comment" warnings in java.sql and java.sql.rowsets

Summary

Address the "no comment" warnings in java.sql and java.sql.rowsets generated by javadoc -Xdoclint

Problem

java.sql and java.sql.rowset contain several classes such as java.sql.BatchUpdateException containing fields and/or methods which are missing a javadoc comment.

Solution

Add the missing comments to the appropriate fields and methods in java.sql and java.sql.rowsets

Specification

Please see the attached diff and webrev for the added javadoc comments (webrev.01 and playground.patch.01)