feat(bigquery): Add cross-region replication support for BigQuery Dataset

[ota2000]

This PR adds support for cross-region replication configuration in BigQuery datasets.

Description

This change introduces the ability to configure cross-region replication for BigQuery datasets through Terraform. The feature allows users to automatically replicate their datasets to specified regions for improved availability and disaster recovery.

Key changes:

• Added new cross_region_replication configuration block
• Added example configuration for cross-region replication
• Added documentation for the new feature

Example Configuration

resource "google_bigquery_dataset" "dataset" {
  dataset_id = "example_dataset"
  location = "US"
  cross_region_replication {
    enabled = true
    replica_regions = [
      "asia-northeast1",
      "europe-west1"
    ]
  }
}

Documentation

Added comprehensive documentation explaining:

• How to enable cross-region replication
• How to specify replica regions
• Limitations and considerations

Release Note

bigquery: added `cross_region_replication` field to `google_bigquery_dataset` resource

Fixes: hashicorp/terraform-provider-google#18185