sql: UDFs with mutations are not allowed in views

A view cannot reference a UDF if the UDF makes has a mutation statement (`INSERT`, `UPDATE`, `UPSERT`, `DELETE`). For example:

```sql
CREATE TABLE t (k INT PRIMARY KEY);
-- CREATE TABLE

CREATE FUNCTION f(i INT) RETURNS VOID LANGUAGE SQL AS $$
INSERT INTO t VALUES (i);
$$;
-- CREATE FUNCTION

CREATE VIEW v AS SELECT f(1);
-- ERROR: INSERT cannot be used inside a view definition
-- SQLSTATE: 42601
```

Jira issue: CRDB-53418

Start by reproducing the SQL example with a mutating UDF referenced by a view, then trace where view definitions reject mutation statements. Add regression coverage for the demonstrated behavior and verify the resulting SQL error or accepted definition matches the intended resolution.

Written by the indexing model from the issue text.