HPCC-11636 Fix JSON output of INIFINITE and NaN real values

The indicators "inf" and "nan" need to be quoted as json
strings. Actual real values are not quoted.

Signed-off-by: Anthony Fishbeck <anthony.fishbeck@lexisnexis.com>
HPCC-11636 Updated to fix raw output format

Also fixed raw output of FlushingStringBuffer::encodeData().

Signed-off-by: Anthony Fishbeck <anthony.fishbeck@lexisnexis.com>
Merge pull request #6282 from afishbeck/jsonRealInfiniteNaN

HPCC-11636 Fix JSON output of INIFINITE and NaN real values

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>