Bug: `SELECT * FROM ( SELECT * FROM APPLICATIONS.SALESFORCE.ACCOUNT) outer` fails to parse in snowflake

I hit a bug where the SQL statement
```sql
SELECT * FROM ( SELECT * FROM APPLICATIONS.SALESFORCE.ACCOUNT) outer
```

failed to parse. This is because `OUTER` is part of the reserved keyword list for table aliases. https://github.com/apache/datafusion-sqlparser-rs/blob/8ccb87a8355858ccb06ffc20484657cd7980d78c/src/keywords.rs#L843-L900

Currently this list is a global but it seems like it should be dialect specific. I'm happy to work on this, but I wanted to know if the project had any opinions on how this list should be maintained at the dialect level.

Start by reproducing the Snowflake query and reading the linked range in src/keywords.rs, especially how OUTER is classified. Then inspect the parser's dialect handling to determine how the reserved-keyword list should be maintained. Done means the reported query parses correctly without regressing keyword handling in other dialects.

Written by the indexing model from the issue text.