Function validate_schema_mod_statements 

pub(crate) fn validate_schema_mod_statements(
    database_name: &str,
    schema_name: &str,
    schema_path: &Path,
    statements: &mut [Statement<Raw>],
    errors: &mut Vec<ValidationError>,
)

Validate schema mod file statements and normalize names.

Schema mod files can only contain:

• COMMENT ON SCHEMA (targeting the schema itself)
• GRANT ON SCHEMA (targeting the schema itself)
• ALTER DEFAULT PRIVILEGES

Names are normalized to include the database qualifier.