support more datetime format

[HarrisChu]

support more datetime format:

• RFC3339
• RFC2822
• ISO8601
• "2011-08-17T11:10:21.570+0000"

(root@nebula) [(none)]> yield datetime("2011-08-17T11:10:21.5Z")
+------------------------------------+
| datetime("2011-08-17T11:10:21.5Z") |
+------------------------------------+
| BAD_DATA                           |
+------------------------------------+
Got 1 rows (time spent 648/2459 us)

Tue, 25 Jan 2022 02:14:54 UTC

(root@nebula) [(none)]> yield datetime("Wed, 17 Aug 2011 11:10:21 GMT")
+-------------------------------------------+
| datetime("Wed, 17 Aug 2011 11:10:21 GMT") |
+-------------------------------------------+
| BAD_DATA                                  |
+-------------------------------------------+
Got 1 rows (time spent 557/2347 us)

Tue, 25 Jan 2022 02:15:16 UTC

(root@nebula) [(none)]> yield datetime("2011-08-17T11:10:21.570000Z")
+-----------------------------------------+
| datetime("2011-08-17T11:10:21.570000Z") |
+-----------------------------------------+
| BAD_DATA                                |
+-----------------------------------------+
Got 1 rows (time spent 426/1916 us)

Tue, 25 Jan 2022 02:15:31 UTC
(root@nebula) [(none)]> yield datetime("2011-08-17T11:10:21.570+0000")
+------------------------------------------+
| datetime("2011-08-17T11:10:21.570+0000") |
+------------------------------------------+
| BAD_DATA                                 |
+------------------------------------------+
Got 1 rows (time spent 520/2908 us)

Tue, 25 Jan 2022 02:23:03 UTC

[HarrisChu]

user cases:

1. have a big data file with datetime string, e.g. "2011-08-17T11:10:21.570+0000"
2. cannot import these data into nebula before converting the datetime format.

[Shylock-Hg]

Yes, our current implementation is almost subset of iso8601, we could extend it by following the BNF described in https://datatracker.ietf.org/doc/html/rfc3339