[C++] Convert `SingularOrList` to `is_in` when possible

### Describe the enhancement requested

Currently, when we encounter `SingularOrList` from Substrait, we convert it into an or list. In other words, `expr1 || expr2 || expr3 || expr4`. However, when all of the expressions are of the form `field == literal` (where `field` is the same) then we can replace it with `is_in(field, [literal1, literal2, ..., literalN])`.

This is arguably a little bit on the "planner/optimizer" slippery slope but it's a simple enough optimization and we already have an `is_in` function so I think it's a reasonable one to apply.

### Component(s)

C++