feat(providers): add BMC Helix ITSM provider

[alpar]

BMC Helix ITSM Provider

Closes #1939

Features

• Pull incidents via BMC Helix simplified REST API (/api/com.bmc.dsm.itsm.itsm-rest-api/incident)
• Create incidents with impact, urgency, priority, service type
• Search incidents with query filters
• Pull topology (CI/CMDB relationships) from BMC Helix CMDB
• Health check and scope validation
• Dual auth: Basic (username/password) and OAuth token

Provider Methods

Method	Description
create_incident	Create a new incident
get_incident	Get incident by ID
search_incidents	Search with query

Authentication

{
  "bmc_base_url": "https://your-instance.onbmc.com",
  "username": "your-user",
  "password": "your-password"
}

Or with OAuth token:

{
  "bmc_base_url": "https://your-instance.onbmc.com",
  "auth_token": "your-oauth-token"
}

Testing

• 10 unit tests covering auth, incident CRUD, topology, alerts, and health check
• Syntax and structure validated against Keep provider base classes

References

• BMC Helix ITSM REST API Docs
• BMC Helix Simplified REST API

[alpar]

Hi @shahargl, CI green — ready for review when you get a chance. Thanks!