Adding support for SQL Server Timezones

[modular-magician]

Fixes: #12705

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sql: added `time_zone` field in `google_sql_database_instance`

Derived from GoogleCloudPlatform/magic-modules#6635

[IchiruTake]

Refer to this issue #12975. Based on the file google/resource_sql_resource_instance.go, the argument time_zone is located inside the settings sub-block but the documentation added it into the sql_server_audit_config. This also raise conflict with the GCP portal as well and caused Terraform code to raise error without notice.

[github-actions]

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