feat: add contracts feature flag to arbiter-core

[Sabnock01]

Moves contracts/ into arbiter-core and adds a feature flag to the crate to include the contracts.

Resolves #573

[codecov]

Codecov Report

Merging #592 (48e46c0) into main (cfb0b5b) will decrease coverage by 1.74%.
Report is 2 commits behind head on main.
The diff coverage is n/a.

❗ Current head 48e46c0 differs from pull request most recent head 4de6f83. Consider uploading reports for the commit 4de6f83 to get more accurate results

@@            Coverage Diff             @@
##             main     #592      +/-   ##
==========================================
- Coverage   60.49%   58.75%   -1.74%     
==========================================
  Files          26       11      -15     
  Lines        5399     3722    -1677     
==========================================
- Hits         3266     2187    -1079     
+ Misses       2133     1535     -598     

see 26 files with indirect coverage changes

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[Autoparallel]

In the arbiter-core lib file, we need to annotate the bindings module like so:

#[cfg(feature = "contracts")]
pub mod bindings; 
pub mod data_collection;
pub mod environment;
pub mod math;
pub mod middleware;
#[cfg(test)]
mod tests;

This may interfere with some tests, so we should be careful of that.

Externally, we should find that only if we have:

arbiter-core = { git = "<your github link>", branch = "<your branch name>", features = "contracts" }

are we able to

use arbiter_core::bindings::*;

Perhaps it's better to rename the module to contracts? What do you think of that change as well?

[Alexangelj]

I like these changes - this is how it should be done.

I know that the tests rely on the bindings of these contracts @Autoparallel , I think keeping some static bindings in the test folder is how we go about keeping the tests in without relying on the generated bindings from these contracts

[Autoparallel]

Nice work!

[Sabnock01]

Feel free to squash