Add Security Monitoring API to dogshell

[clementgbcn]

Cloud SIEM API Support

Overview

This PR adds support for Cloud SIEM rule management and security signals retrieval in the Datadog Python API client.

Changes

• Added SecurityMonitoringRule class to manage SIEM rules:

  • Get all security monitoring rules
  • Get a specific security monitoring rule
  • Create a new security monitoring rule
  • Update an existing security monitoring rule
  • Delete a security monitoring rule

• Added SecurityMonitoringSignal class to retrieve and manage security signals:

  • Get all security signals with filtering options
  • Get a specific security signal's details
  • Search for security signals with custom query filters
  • Change the triage state of security signals (open, archived, under_review)

• Added dogshell commands for security monitoring:

  • dogshell security-monitoring rules list: List all security monitoring rules
  • dogshell security-monitoring rules get <rule_id>: Get a specific rule
  • dogshell security-monitoring rules create --file <rule.json>: Create a new rule
  • dogshell security-monitoring rules update <rule_id> --file <rule.json>: Update a rule
  • dogshell security-monitoring rules delete <rule_id>: Delete a rule
  • dogshell security-monitoring signals list: List security signals
  • dogshell security-monitoring signals get <signal_id>: Get a specific signal
  • dogshell security-monitoring signals triage --state <state> <signal_id>: Change triage state

• Added basic unit tests for new API classes

• Updated CHANGELOG.md

Tests

• Added a basic unit test to ensure classes are defined correctly
• More comprehensive testing will be added in a follow-up PR

Documentation

The API follows the standard Datadog REST API patterns described in:
https://docs.datadoghq.com/api/latest/security-monitoring/