feat: data_source_okta_groups add sorting and timestamp fields

[exitcode0]

Summary

Adds sorting capabilities and timestamp field to the schema of okta_groups data source
Enables better control over result ordering and access to previously unavailable group metadata

New Features

• Sorting Parameters: sort_by and sort_order for API-level sorting
• Timestamp Fields: created, last_updated, last_membership_updated as computed attributes
• Supported Sort Fields: created, lastUpdated, lastMembershipUpdated, id, name
• Sort Orders: asc and desc
• Add tests for new sorting functionality
• Update documentation with new examples and schema details

Example Configuration

data "okta_groups" "recent" {
  q          = "Engineering"
  sort_by    = "created"
  sort_order = "desc"
}

output "latest_group" {
  value = data.okta_groups.recent.groups[0].created
}

fixes #2466