BigQuery Dialect - CREATE TABLE CLONE and COPY

Hi, All

just wondering if there is a support coming for these bigquery statements?

```
CREATE TABLE `tbl`
CLONE `src_tbl`;
```
```
CREATE TABLE `tbl`
COPY `src_tbl`
```
reference: https://cloud.google.com/bigquery/docs/reference/standard-sql/data-definition-language#create_table_copy

currently, I'm encountering this limitation below.

```
com.google.zetasql.SqlException: CREATE TABLE CLONE is not supported [at 4:7]
```

edit: it seems COPY is supported, only CLONE is not supported.

Thank you!