DRILL-2565: Add some key "already-closed" checks, with test for future DRILL-2489 work.
- Created AlreadyClosedSqlException.
- (Moved JdbcApiSqlException to be subclass of SQLNonTransientException.)
- Created test Drill2489CallsAfterCloseThrowExceptionsTest for eventual fixing
of DRILL-2489.
- (Is partial: Covers Connection, Statement, and ResultSet.)
- (Is interim: Most methods' tests disabled with @Ignore("...DRILL-2489...").)
- Added already-closed checking in key places, especially those that involve
communication and could hang for a while rather than dying quickly (e.g.,
Statement.execute...(...)).
