Some expressions can end up with unintended `DETACHED`

[scotttrinh]

When attempting to cast a subselect into JSON, this expression generates incorrect EdgeQL

    const q = e.select(e.Movie, (movie) => ({
      node: movie,
      cursor: e.to_str(
        e.cast(
          e.json,
          e.select(movie, () => ({
            id: true,
            release_year: true,
          })),
        ),
      ),
    }));

    WITH
      __scope_0_defaultMovie := DETACHED default::Movie
    SELECT __scope_0_defaultMovie {
      single node := __scope_0_defaultMovie,
      single cursor := (
        std::to_str((<std::json>(SELECT DETACHED default::Movie {
          id,
          release_year
        })))
      )
    }

Notice the DETACHED default::Movie in the sub-select. This should be __scope_0_defaultMovie.

This is a somewhat recent regression since the project rename, so that should narrow the offending issue down to something in our recent updates to the automatic with extraction logic.

---

Note, that it does work if you return a Free Object instead of the subselect:

    const q = e.select(e.Movie, (movie) => ({
      node: movie,
      cursor: e.to_str(
        e.cast(
          e.json,
          e.select({
            id: movie.id,
            release_year: movie.release_year,
          }),
        ),
      ),
    }));