Parser fails to parse quoted identifiers in FOR .. IN loop

**Describe the problem**

The `FOR .. IN` loop should allow for using quoted identifiers just like any other syntactic element, but it currently doesn't.

**To Reproduce**

This doesn't compile:

```sql
create procedure "proc_ForIndexedLoop"()
language plpgsql
as $$
begin
for "i" in 1 .. 10 loop
raise notice '%', "i";
end loop;
end;
$$
```

It fails with this error:

```
SQL Error [42703]: ERROR: column "i" does not exist
```

**Expected behavior**

It should compile just like in PostgreSQL. The workaround is to not quote the identifier:

```sql
create procedure "proc_ForIndexedLoop"()
language plpgsql
as $$
begin
for i in 1 .. 10 loop
raise notice '%', "i";
end loop;
end;
$$
```

**Environment:**
- CockroachDB version: CockroachDB CCL v25.2.1 (x86_64-pc-linux-gnu, built 2025/06/02 23:17:23, go1.23.7 X:nocoverageredesign)
- Server OS: Linux on Docker on Windows
- Client app: JDBC

Jira issue: CRDB-51911

Start by reproducing the SQL example and trace the parser entry point for quoted identifiers in a FOR .. IN loop. Compare it with the unquoted workaround and PostgreSQL behavior, then add coverage showing that the quoted procedure compiles and runs correctly.

Written by the indexing model from the issue text.