Refactoring contracts macro logic into separate modules

[JustusAdam]

Refactors the contracts module into several smaller modules grouped by task. The previous modules was very long and interleaved a lot of logic for various parts of the contracts state machine. This refactoring groups functions by specificity, task correlation and reusability.

All code changes here are exclusively moves with no changes to functionality.

The split is as follows:

• mod.rs contains definitions of the data structures used to handle contracts, the entry point for contract handling, as well as a documentation overview.
• bootstrap.rs is the logic that initialized the central data structures, such as the handler and the functions state
• check.rs is all the logic required to create the function that checks a contract.
• replace.rs is all the logic required to create a function that abstracts via contract
• shared.rs are Kani/contract-specific helper functions that are used in more than one of bootstrap, check or replace
• helpers.rs are Kani/contract-independent helper functions

I was going to make the old PR but I shudder at the though of appending more logic to the extremely long contracts.rs file so I figured I'd split the logic real quick before adding more.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 and MIT licenses.

[feliperodri]

LGTM.

[celinval]

Awesome! This looks much cleaner. Thank you, @JustusAdam!

I'm assuming there was no change in the logic, just moving stuff around, right?

[JustusAdam]

Yes. The only "code" that changed is that some functions are now "pub". Other than that there wasn't anything.

Does anyone know what's up with this release bundle failure?

[feliperodri]

Does anyone know what's up with this release bundle failure?

I have no idea. @celinval do you have permission to re-trigger that job?