Add language runtime

[Jujumba]

Problem

At this point, Pitusya is just an interpter that does almost nothing: condionals and function do not make sense without IO operations.

Standard library implementation will resolve this issue

[Jujumba]

Runtime is ready

But issue will be closed when there would be enough functions

[Jujumba]

It has been moved here: https://crates.io/crates/pitusyastd