fix: parse MySQL simple-form CREATE FUNCTION in multi-statement scripts

[kalayciburak]

What is wrong

MySQL simple-form CREATE FUNCTION (body is RETURN expr without BEGIN...END) failed to parse when another statement followed in the same script:

SQLUtils.parseStatements(
        "CREATE FUNCTION f() RETURNS INT RETURN 1;\nSELECT 1;", "mysql");
// ParserException: not supported. ... token SELECT

BEGIN...END bodies were already fine.

The function body was parsed with parseStatement(), which treats leftover tokens as an unexpected end of the statement. The trailing semicolon was also consumed on the RETURN body, so the outer statement list did not see a terminator on the CREATE FUNCTION itself.

How this PR fixes it

• Parse the simple-form body with parseStatement0() so a following statement in the same script is left for the caller.
• If the function/procedure body already consumed the terminator, treat the CREATE as complete in parseStatementList.

Fixes #6705

Tests

Executed:

mvn test -pl core -Dtest=MySqlCreateFunctionMultiStatementTest,SQLServerCreateFunctionTest

Results: Tests run: 10, Failures: 0, Errors: 0, Skipped: 0

Also mvn test -pl core -Dtest=*CreateFunction* (same 10 tests) and checkstyle: 0 violations.

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