Make COLUMNS clause optional

[Dtenwolde]

Currently the SELECT * is optional for DuckDB's parser. I think it would be also good to make the COLUMNS clause optional. Such that the following queries are equivalent:

SELECT a.id, b.id
FROM GRAPH_TABLE(snb MATCH (a:Person)-[k:knows]->(b:Person))

FROM GRAPH_TABLE(snb MATCH (a:Person)-[k:knows]->(b:Person) COLUMNS(a.id, b.id))

See section 7.1 point a of the SQL/PGQ specifications

This could tie in with making the variable name at the end of the GRAPH_TABLE clause optional (would need to be another issue)

[Dtenwolde]

How should things like ELEMENT_ID(a) be handled if they are in the outer SELECT.