Fix node order

[asdine]

This PR fixes the order of the nodes generated by the parser. Projections are supposed to happen before sorting and limit/offset.

EXPLAIN SELECT a + 1 FROM test WHERE c > 30 ORDER BY a DESC LIMIT 10 OFFSET 20

Before:

Table(test) -> σ(cond: c > 30) -> Sort(a DESC) -> Offset(20) -> Limit(10) -> ∏(a + 1)

After:

Table(test) -> σ(cond: c > 30) -> ∏(a + 1) -> Sort(a DESC) -> Offset(20) -> Limit(10)