Implement a macro checking experimental_features during building project config

[tomek0123456789]

Problem

I have an idea how to ensure in compile-time that the list of experiments is exhaustive:
Write a macro (macro_rules!), which usage would look like this:

experimental_features!(ExperimentalFeatues, [negative_impls,something_else,etc])

which would expand to something like this:

// Struct name is the first argument to the macro.
struct ExperimentalFeatures(HashSet<SmolStr>);

impl ExperimentalFeatures {
    fn new_checked(values: HashSet<SmolStr>, package: PackageId, ui: &Ui) -> Self {
        for feature in &values {
             match feature {
                 "negative_impls" => {},
                 "something_else" => {},
                 "etc" => {},
                 _ => ui.warn(&format!("{package}: unknown experimental feature: {feature}"))
             }
        }
        Self(values)
    }

    fn to_compiler_features(&self) -> cairo_lang_filesystem::db::ExperimentalFeaturesConfig {
        // Rust compiler will check exhaustiveness here
        cairo_lang_filesystem::db::ExperimentalFeaturesConfig {
            negative_impls: self.0.contains("negative_impls"),
        }
    }
}

Do it here (compiler config) and here (snforge-test-collector)

Additionally, add checking for fields that are not in ExperimentalFeaturesConfig and raise warnings for those not in the struct (probably before parsing it into Manifest, here). Add a test checking that, too.

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Search in code by phrase TODO (#1040)

Originally discussed here.

Proposed Solution

No response

Notes

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