MGCA: Support for tuple constructors
r? BoxyUwU
part of https://github.com/rust-lang/rust/issues/132980fixesrust-lang/rust#136379fixesrust-lang/rust#138132
i tried to keep implementation very minimal and it's very similar to how structs was implemented with small adjustments
this does not make const constructor like None works, just something like Some(n)
todo:
* ~~tests~~
* write a better description (not sure if needed)
* add more comments and FIXMEs from structs code