[Feature] Allow mix of generic and typed parameters in functions

**Is your feature request related to a problem? Please describe.**
As we currently don't support union types, developers should be allowed to use generic types in cases where union types would be a good fit.

**Describe the solution you'd like**
Remove the error saying: `Function '{name}' has a mix of generic and typed arguments`

**Additional context**
This error can later be introduced in a form of a warning to make it less strict than it is right now.