feat: support select into statement

[jingchen2222]

• Please check if the PR fulfills these requirements

• The commit message follows our guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)
  feature
• What is the current behavior? (You can also link to an open issue here)

OpenMLDB Issue:
4paradigm/OpenMLDB#455

SELECT col1, col2, col1+col2 from t1 into outfile 'data.csv' OPTIONS(charset='utf-8');

• What is the new behavior (if this is a feature change)?
  Supprt SELECT ... INTO... syntax

1. support ASTSelectIntoStatement
2. allow guess ASTSelectIntoStatement with ASTQueryStatement
3. update keywords

• Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)

• Other information: