Add ParameterTuple to std.typecons

I often find myself in the need of writing / copy-pasting this code whenever I have a project where I need to do some meta-programming on functions.
It's basic, does one job, and is way simpler to start with than using an `is` expression.

I was not sure where to put it though, as we don't have anything similar to `std.meta.codegen`.
No `Params:` block, no `Returns:` block.