Cypher randomUUID() function implemented PG13

[Allison-E]

• Works the same way as the cypher randomUUID() function.
• Works only on PostgreSQL 13 or higher since the gen_random_uuid() function in PostgreSQL was introduced in version 13.
• Added regression tests for it.

[rafsun42]

@Allison-E

randomUUID is not in open cypher spec.

Also, it can be done like this-

(pg-15.4) agedev=# SELECT * from cypher('graph', $$
    RETURN pg_catalog.gen_random_uuid()    
$$) as (result text);
                result                
--------------------------------------
 1d99c524-5746-400c-a94f-c5f89840b2b1

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