DRILL-2465: Fix multiple DatabaseMetaData.getColumns() bugs.

- Added test DatabaseMetaDataGetColumnsTest.
- (Renamed Drill2128GetColumnsBugsTest to
  Drill2128GetColumnsDataTypeNotTypeCodeIntBugsTest.)
- Fixed/implemented various columns:
  - Added COLUMN_SIZE (big CASE expression handling lots of cases).
  - Fixed DECIMAL_DIGITS.
  - Fixed NUM_PREC_RADIX.
  - ~Fixed REMARKS ('' -> NULL).
  - ~Fixed COLUMN_DEF ('' -> NULL).
  - Fixed CHARACTER_OCTET_LENGTH.
  - Fixed ORDINAL_POSITION.
  - Fixed SCOPE_CATALOG, SCOPE_SCHEMA, SCOPE_TABLE,
  - Fixed SOURCE_DATA_TYPE.
- Note:  INTERVAL types have only *interim* implementations.
  (INFORMATION_SCHEMA.COLUMNS fixes are needed for completion.)
- Added canonical data type name strings in DATA_TYPE -> TYPE_NAME CASE
  expression (for robustness for expected upcoming INFORMATION_SCHEMA.COLUMNS
  standard-compliance bug fixing).