Fixes#1298
- Fixes Limbo trying to use an index using a WHERE clause constraint
that refers to the same table on both sides, e.g. `WHERE t.x = t.x`
- Fixes not using indexes when the relevant expression is paren wrapped,
e.g.
- `SELECT * FROM t WHERE (indexcol) > 5`
- `SELECT * FROM t WHERE (indexcol > 5)`
- Changes existing table logical expr fuzz test to have primary keys
(which helped me find both issues above)
Closes#1300
e0e031d8af