[LesterEvSe]

Scope has grown too large and handles many unrelated responsibilities at once:

/// Scope for generating the abstract syntax tree.
///
/// The scope is used for:
/// 1. Assigning types to each variable
/// 2. Resolving type aliases
/// 3. Assigning types to each witness expression
/// 4. Resolving calls to custom functions
pub(super) struct Scope {
    /// Current position in the module tree. Push on `mod` enter, pop on exit.
    /// Empty path means we are at the root (main file) scope.
    pub(super) module_path: Vec<ModuleName>,

    /// Global scope where items from the main file that live at the root level.
    root: ModuleScope,

    /// Block-level variable scopes. Push on block enter, pop on block exit.
    variables: Vec<HashMap<Identifier, ResolvedType>>,
    parameters: HashMap<TemplateProgramWitness, ResolvedType>,
    witnesses: HashMap<TemplateProgramWitness, ResolvedType>,
    /// Allow enum constructions to name an enum by its declared name even
    /// when that name is not an alias in scope. Enabled only for value
    /// parsing (witness and argument files), which runs without a scope.
    pub(super) unscoped_enum_names: bool,
    is_main: bool,
    call_tracker: CallTracker,
    pub(super) jet_hinter: Box<dyn JetHinter>,
    /// Errors reported during analysis that did not stop it.
    pub(super) diagnostics: Vec<Diagnostic>,
}

This PR splits it into several smaller structs and replaces the pub(super) fields with getters.

Scope is now much simpler:

/// Scope for generating the abstract syntax tree.
///
/// The scope is used for:
/// 1. Assigning types to each variable
/// 2. Resolving type aliases
/// 3. Assigning types to each witness expression
/// 4. Resolving calls to custom functions
pub(super) struct Scope {
    modules: ModuleTree,
    locals: Locals,
    parts: ProgramParts,

    is_main: bool,
    /// Allow enum constructions to name an enum by its declared name even
    /// when that name is not an alias in scope. Enabled only for value
    /// parsing (witness and argument files), which runs without a scope.
    unscoped_enum_names: bool,
    jet_hinter: Box<dyn JetHinter>,
    /// Errors reported during analysis that did not stop it.
    diagnostics: Vec<Diagnostic>,
}

Checklist

• New or changed language features are used in fixtures/kitchen_sink.simf (see its header).

[KyrylR]

ACK 258e027; successfully ran local tests

[LesterEvSe]

Polished some code after that

[KyrylR]

ACK cafba5e; successfully ran local tests

Ran tests and CI on every commit

[LesterEvSe]

Kyrylo previously suggested some minor improvements to the AST, such as replacing pub(super) fields with getters. I also noticed that Scope could be split into several smaller structs.
It has no breaking changes, so we merged it