`std::any::type_name_of_val` can't guarantee different strings for different types

Currently the API relies upon std::any::type_name_of_val to check that the hooked function and the replacement function has the same signature.

From the documentation for type_name:

The returned string must not be considered to be a unique identifier of a type as multiple types may map to the same type name.

and type_name_of_val:

In short: use this for debugging, avoid using the output to affect program behavior

Here is an example repo where injectorpp thinks to function types are the same, but they are not, causing undefined behavior: https://github.com/tyilo/injectorpp-ub

You should be able to avoid this by introducing a generic type for the actual type of the function, something like:

impl InjectorPP {
    pub fn when_called(&mut self, func: FuncPtr<T>) -> WhenCalledBuilder<'_, T> {
        ...
    }
}

impl WhenCalledBuilder<'_, T> {
    pub fn will_execute_raw(self, target: FuncPtr<T>) {
        ...
    }
}

Start by locating the implementation of when_called and will_execute_raw, then inspect how std::any::type_name_of_val compares function signatures. Use the linked injectorpp-ub example to understand the failure; done means signature validation no longer depends on type-name strings and the proposed generic function types are supported.