Nan related

[czpmango]

Nebula does not define NaN and some computational behavior is inconsistent with Neo4j.
But I think Nebula's test result is also reasonable.If confirmed, I will close this issue.

neo4j test:

neo4j@neo4j> return 0.0/0.0;
+---------+
| 0.0/0.0 |
+---------+
| NaN     |
+---------+

1 row available after 24 ms, consumed after another 0 ms
neo4j@neo4j> return 0.0/0.0>'a';
+-------------+
| 0.0/0.0>'a' |
+-------------+
| NULL        |
+-------------+

nebula test:

(czp@nebula) [nba]> yield 0.0/0.0
+-------------+
| (0/0)       |
+-------------+
| DIV_BY_ZERO |
+-------------+
Got 1 rows (time spent 1222/1749 us)

Wed, 20 Jan 2021 10:08:28 CST

(czp@nebula) [nba]> yield 0.0/0.0>'a'
+-------------+
| ((0/0)>a)   |
+-------------+
| DIV_BY_ZERO |
+-------------+