create std::prelude, reexport Context, and include in module

[g-r-a-n-t]

What is wrong?

There should be a prelude module in the standard library that reexports things like std::context::Context.

i.e.

# std/src/prelude.fe

pub use `ingot::context::Context`
...

The items in this module should be included in every module.

How can it be fixed

I'm not sure on the best approach here. Either we programmatically include the items in analysis or add a use std::prelude::* to the AST of every module before analysis.