Add `ignore-rust-version` flag to `sp1-helper`

[ratankaliani]

Add ignore-rust-version flag compatibility to sp1-helper. When crates such as alloy require a Rust version greater than the Succinct Rust toolchain's version, we need to run cargo prove build --ignore-rust-version.

However, sp1-helper does not have compatibility for this, so developers need to manually run cargo prove build --ignore-rust-version to get their programs to compile.

Specifically, optionally configure a flag to be added to this command:

https://github.com/succinctlabs/sp1/blob/e413e82e86ef97007094d830da1d3b278075a4bc/helper/src/lib.rs#L64-L70