Update identifier defition in MySQL BaseRule.g4 file according to MySQL 8.4 doc

[strongduanmu]

Feature Request

Is your feature request related to a problem?

No

Describe the feature you would like.

With the release of MySQL 8.4, ShardingSphere needs to update the identifier rules in BaseRule.g4 to adapt to MySQL non-reserved keywords, which can be used directly as identifiers without quotes.

Of course, I found that the non-reserved keywords before 8.4 were not fully added to the g4 file, such as zone, so this is a good opportunity to update the identifier. Let's make it more perfect together.

For MySQL non-reserved keywords, you can refer to: https://dev.mysql.com/doc/refman/8.4/en/keywords.html#keywords-in-current-series