HPCC-10908 Add self test for language files

Fixes HPCC-10908

Signed-off-by: Gordon Smith <gordon.smith@lexisnexis.com>
Merge pull request #5451 from GordonSmith/LanguageHelper

HPCC-10908 Add self test for language files

Reviewed-By: Miguel Vazquez <miguel.vazquez@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>