HPCC-10977 Categorise the code generator warnings

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
HPCC-10977 Fix warnings in the code generator

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
HPCC-10977 Add warning categories to the parser

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
HPCC-10977 Minor changes following code review

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #5827 from ghalliday/issue10977

HPCC-10977 Categorise the code generator warnings

Reviewed-By: Jamie Noss <james.noss@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>