MySQL function not implemented: STATEMENT_DIGEST

## Function Information
**Function Name**: `STATEMENT_DIGEST`
**Category**: encryption

## MySQL Function Description
MySQL STATEMENT_DIGEST function:
STATEMENT_DIGEST(statement) - Returns the statement digest hash value as a string.

## Expected Behavior
Expected behavior:
According to MySQL documentation, the function should return correct results.

## Current Behavior in MatrixOne
This function is not implemented in MatrixOne.

**Error Message**: `(20105, "not supported: function or operator 'statement_digest'")`

## Test Case
```sql
SELECT STATEMENT_DIGEST('SELECT 1') AS result1
```

## MySQL Documentation
- [MySQL Official Documentation](https://dev.mysql.com/doc/refman/8.4/en/encryption-functions.html#function_statement-digest)

## Request
Please implement the `STATEMENT_DIGEST` function to improve MySQL compatibility.