Refactor error handling

[kevaundray]

Currently, the code has a lot of unstructured error variants, which seem to be a code smell.

There is already an issue open for this, however it seems that changing the way we handle errors would be better. Rust for example uses structs and proc macros for example, which is analogous to the error variant strategy. rslint on the other hand, seems to inline their errors.

The first step towards closing this would be to refactor noirc_errors

[kevaundray]

This now seems like a copy of #11, so closing