Implement WithVal

[AdrianJendo]

• Implemented WithVal functionality for seamock lib

Example usage:

#[seamock]
pub trait Test {
    fn a(&self, x: i32, y: bool) -> i32;
    fn b(&self) -> u8;
    fn c(&self) -> i32;
}

let mut mock: MockTest = MockTest::new();
let x: i32 = verifier::any!();
let y: bool = verifier::any!();

verifier::assume!(x < 10);
verifier::assume!(y == true);

mock.with_a((WithVal::Lt(15), WithVal::Eq(true)))