feat: add XBG rails

[christinaexyou]

Description

Adds a XGB based rail to detect spam content in data to NeMO Guardrails.

Related Issue(s)

Addresses part of #1303. TrustyAI reviewers include @RobGeada @m-misiura

Checklist

• [x] I've read the CONTRIBUTING guidelines.
• [x] I've updated the documentation if applicable.
• [x] I've added tests if applicable.
• [x] @mentions of the person or team responsible for reviewing proposed changes.