Presto: Transpiling SEQUENCE with alias to UNNEST(SEQUENCE(...)) has incorrect alias

[vegarsti]

#1527 implemented a fix for transpiling SEQUENCE to Presto, so we now wrap SEQUENCE in an UNNEST call if used as a source. But there's an edge case left, where if we original SEQUENCE has an alias, that alias is not translated properly to the Presto code.

Code snippet

>>> import sqlglot
>>> sqlglot.__version__
'12.3.0'
>>> sqlglot.transpile("SELECT * FROM t CROSS JOIN GENERATE_SERIES(2, 4) s", read="postgres", write="presto")[0]
'SELECT * FROM t CROSS JOIN UNNEST(SEQUENCE(2, 4)) AS s'

The unnest requires a tuple (?) alias, so we need s to be _u(s) (like in #1495). Thus the transpiled SQL here should be

SELECT * FROM t CROSS JOIN UNNEST(SEQUENCE(2, 4)) AS _u(s)