Move starknet/rust deps to separate package

[weiihann]

This PR moves the Rust dependencies and FFI functions in the starknet package to a separate subpackage called starknet/compiler.

FFI code may have specific build requirements or dependencies. Isolating it in a subpackage allows us to manage these dependencies more effectively without impacting the higher level package.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 75.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 78.56%. Comparing base (0c0700c) to head (92fa102). Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
rpc/class.go	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #2148 +/- ## ========================================== + Coverage 78.44% 78.56% +0.11% ========================================== Files 100 100 Lines 9191 9191 ========================================== + Hits 7210 7221 +11 + Misses 1348 1343 -5 + Partials 633 627 -6 ```

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