support create table..clone and alter table...swap

[reata]

CREATE TABLE CLONE:

create table tab2 CLONE tab1

Ref:

• https://cloud.google.com/bigquery/docs/table-clones-create
• https://docs.snowflake.com/en/sql-reference/sql/create-clone

---

ALTER TABLE SWAP WITH:

alter table tab1 swap with tab2

Ref:

• https://docs.snowflake.com/en/sql-reference/sql/alter-table