Expose dependencies information in scarb metadata

[mkaput]

Problem

Since 2.9 Cairo adds a notion of crate dependencies which limit visibility of other crates in each crate within a compilation unit.

Scarb resolver is the place where all the necessary information for building all dependencies is generated, and Scarb itself is capable of passing this information to the compiler. Unfortunately, other tools (CairoLS, scarb doc, cairo lint) also need it, and currently they have to copy the complex logic from Scarb codebase.

Proposed Solution

Add the following properties to scarb metadata --format-version 1:

struct CompilationUnitComponentMetadata {
    // Option for backwards compatibility
    /// Unique string identifying this component.
    pub id: Option<CompilationUnitComponentMetadataId>,
    pub dependencies: Option<Vec<CompilationUnitComponentDependencyMetadata>>,
}

struct CompilationUnitComponentMetadataId { /* same kind as PackageId etc. */ }

struct CompilationUnitComponentDependencyMetadata {
    /// Id of component from the same compilation unit that this dependency refers to.
    ///
    /// This should directly translate to a `discriminator` field in Cairo compiler terminology,
    /// except that it should be `None` for `core` crate **only**.
    pub id: String,

    pub extra // same story as everywhere
}

Notes

No response