Revert "[SIG-45721] don't interpret QUALIFY as table alias (#13)"

This reverts commit cf4bd95.

Author: jmhain

src/dialect/keywords.rs

@@ -559,8 +559,6 @@ pub const RESERVED_FOR_TABLE_ALIAS: &[Keyword] = &[
     Keyword::USING,
     // for MSSQL-specific OUTER APPLY (seems reserved in most dialects)
     Keyword::OUTER,
-    // for Snowflake QUALIFY
-    Keyword::QUALIFY,
 ];
 
 /// Can't be used as a column alias, so that `SELECT <expr> alias`