Entity Analytics Okta: add support for ECS entity fields

[chemamartinez]

Proposed commit message

Adds ECS entity field support to the Okta Entity Analytics integration
for both the entity and user data streams.

Maps device managed status, OS version, user last activity, manager
relationships, MFA status, role permissions, enrolled devices, and
direct reports to host.entity.* and user.entity.* fields:

- host.os.version from device profile osVersion
- host.entity.attributes.managed from device profile managed field
- user.entity.lifecycle.last_activity from last_login timestamp
- user.entity.relationships.administered_by (user_id, username) from
  the user's manager profile fields
- user.entity.attributes.mfa_enabled set to true when the user has at
  least one ACTIVE factor. Requires the new enrich_user_factors option,
  which adds one API request per user to /api/v1/users/{id}/factors
- user.entity.attributes.permissions from the labels of custom role
  permissions. Requires the new enrich_user_perms option, which enables
  role enrichment and adds one API call per custom role per user to
  /api/v1/iam/roles/{roleId}/permissions
- user.entity.relationships.owns ({host_id, hostname}) from the list of
  enrolled devices. Requires the new enrich_user_devices option, which
  adds one API request per user to /api/v1/users/{id}/devices
- user.entity.relationships.supervises ({user_id, email, username}) from
  the direct reports list. Requires the new enrich_user_supervises option,
  which is derived server-side from managerId with no extra API calls

Checklist

• I have reviewed tips for building integrations and this pull request is aligned with them.
• I have verified that all data streams collect metrics or logs.
• I have added an entry to my package's changelog.yml file.
• I have verified that Kibana version constraints are current according to guidelines.
• I have verified that any added dashboard complies with Kibana's Dashboard good practices

Related issues

• Closes Entity Analytics Okta: add support for entity fields #18290

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