Implementing Type Hints of Let expressions for Wildcards

[Tarbetu]

In previous PR, I have implemented type hints for ID's like this:

let x: Number = 5

However, it wouldn't work for wildcards:

let _: Number, _x: Number = 5, 10

This PR allows the usage of type hints with wildcards.

[irh]

This is great @Tarbetu - would you be up for also adding a couple of runtime tests in vm_tests.rs? This would show that the compiler side is also hooked up correctly.

[Tarbetu]

Ok, I will do it when I'm free :)

[Tarbetu]

Tests are ready.

[irh]

@Tarbetu Thanks, but I should have been clearer, sorry. There are already tests for let expressions in vm_tests.rs (search for type_checks), I meant that a test or two should be added for using type hints on wildcards.

[Tarbetu]

Oh. 🤦🏼

Sorry for misunderstood. I reimplemented tests as wanted, but I'm not sure that they are presenting the proper scenario.

[irh]

No worries, I should have been clearer. Thanks for the PR!