HPCC-11813 Add tooltip to grid headings

Fixes HPCC-11813

Signed-off-by: Gordon Smith <gordon.smith@lexisnexis.com>
Merge pull request #6180 from GordonSmith/HPCC-11813

HPCC-11813 Add tooltip to grid headings

Reviewed-By: Miguel Vazquez <miguel.vazquez@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>