MITRE endpoints can't sort by references.external_id

[frankeros]

Wazuh version	Component
4.3.x	API

Related to	#7819

Description

The Wazuh Kibana App needs to sort the MITRE endpoints by the external_id field that is included in the references.
This field that is important for the users is the public ID for the MITRE resources.
Maybe it should be included in the main object.

[davidjiglesias]

We have decided to move source, url and external_id (only external_id object from current references list) to the exterior level of the response for all MITRE endpoints.

[mcarmona99]

Checks

wazuh/wazuh

• Unit tests without failures. Updated and/or expanded if there are new functions/methods/outputs:
  • Cluster (framework/wazuh/core/cluster/tests/ & framework/wazuh/core/cluster/dapi/tests/)
  • Core (framework/wazuh/core/tests/)
  • SDK (framework/wazuh/tests/)
  • RBAC (framework/wazuh/rbac/tests/)
  • API (api/api/tests/)
• API tavern integration tests without failures. Updated and/or expanded if needed (api/test/integration/):
  • Affected tests
  • Affected RBAC (black and white) tests
• Review integration test mapping using the script (api/test/integration/mapping/integration_test_api_endpoints.json)
• Review of spec.yaml examples and schemas (api/api/spec/spec.yaml)
• Review exceptions remediation when any endpoint path changes or is removed (framework/wazuh/core/exception.py)
• Changelog (CHANGELOG.md)

wazuh/wazuh-documentation

• Migration from 3.X for changed endpoints (source/user-manual/api/equivalence.rst)
• Update RBAC reference with new/modified actions/resources/relationships (source/user-manual/api/rbac/reference.rst)