Support UNWIND in the lance-graph

[ChunxuTang]

Currently, Cypher supports the UNWIND keyword

UNWIND [1, 2, 3] AS num
RETURN num

We want to support that in the lance-graph.

1. One potential way to achieve this is by using the unnest method in the DataFusion. E.g., the previous Cypher query can be translated to

SELECT unnest(make_array(1,2,3)) AS num

2. Another potential approach is to use the UNION strategy (similar to the variable-length paths). E.g., the previous Cypher query can be translated to

SELECT 1 AS num
UNION ALL
SELECT 2 AS num 
UNION ALL
SELECT 3 AS num

[ChunxuTang]

Cc @leiyuou