Return backend API errors to ntlm_auth_wrapper

[stgmsa]

Description

Return detailed backend errors when there's an authentication failure to ntlm_auth_wrapper, and FreeRadius will be able to log this and forwarded to radius audit logs for further query.

Impacts

• when ntlm_auth_wrapper exitd with errors, a non-zero exit code (ranges from 1-5) will always be returned, previously was always returned with 1.
• when ntlm_auth_wrapper exited with errors, a more detailed error message will be returned.

Issue

fixes #8158

Delete branch after merge

YES

Checklist

(REQUIRED) - [yes, no or n/a]

• [no] Document the feature
• [no] Add OpenAPI specification
• [no] Add unit tests
• [no] Add acceptance tests (TestLink)

Enhancements

adds more detailed error messages when authentication failed, categorized common errors and associate with individual return codes.

Bug Fixes

fix #8158

UPGRADE file entries

bin/ntlm_auth_wrapper.c