fix(engine) Fix question marks simplification with deref/borrow.

[maximebuyse]

Fixes #1299

The problem is that in this case we have a match branch:

core::ops::control_flow::ControlFlow_Continue(val) => {
    &(deref(val))
}

and the phase expects the usual:

core::ops::control_flow::ControlFlow_Continue(val) => {
    val
}

I tried moving Simplify_question_marks after Drop_references, but this means moving it after Direct_and_mut which also messes with the pattern needed to be recognized for question marks...

[W95Psp]

Thanks! I think making the pattern more flexible is the way to go.