Add structured generic metadata support

[dacowan]

Summary

Adds structured generic type metadata to @minecraft/api-docs-generator and corresponding rendering support to @minecraft/markup-generators-plugin.

Metadata producers can now describe ordered generic declarations and recursive generic applications as data. The generators use that structure consistently across TypeScript declarations, MSDocs, cross-module links, and changelogs.

Why

The metadata model could describe concrete types but could not preserve relationships such as Container<T>, generic methods, nested applications, or generic inheritance without relying on pre-rendered TypeScript text.

Structured metadata is useful when the relationship can be represented directly: it remains machine-readable, participates in recursive type processing, and can be rendered consistently by every output format.

This does not replace the existing raw_script_text path. TypeScript-specific constructs such as conditional types, mapped types, indexed-access types, template-literal types, and complex type aliases remain better represented as TypeScript.

Metadata contract

The model adds:

interface MinecraftGenericTypeParameter {
    name: string;
    constraint?: MinecraftType;
    default?: MinecraftType;
}

• generic_class_types on classes and interfaces
• generic_function_types on functions and methods
• generic_base and ordered generic_types on type records

Generic parameter and argument arrays preserve source order. All fields are optional, so existing non-generic metadata remains valid.

Generator behavior

• Recursively processes generic bases, arguments, constraints, and defaults through existing type mapping and dependency resolution.
• Renders generic classes, interfaces, functions, methods, properties, return types, arrays, optionals, and inheritance.
• Preserves cross-module imports and MSDocs links for types nested inside generic applications.
• Compares generic declarations and applications in changelogs while preserving semantic array order and ignoring dependency-version-only changes.
• Emits one module-local structural NativeClass<T> helper when a valid reserved application is used, with validation for argument cardinality and public-name collisions.
• Keeps existing non-generic interface and declaration behavior unchanged.

The producer-facing contract and ordering requirements are documented in tools/api-docs-generator/README.md.

Compatibility and scope

The new metadata fields are additive and optional. Existing non-generic fixtures and snapshots remain unchanged, and this PR does not modify production declaration output.

The structured model intentionally does not attempt to represent the complete TypeScript type system. Generic type-alias declarations, constructor type parameters, conditional and mapped types, variance, higher-kinded types, and raw TypeScript fragments remain outside its scope.

raw_script_text continues to work as before and does not trigger structured NativeClass<T> helper synthesis.

Validation

• @minecraft/api-docs-generator: build, lint, and tests pass.
• @minecraft/markup-generators-plugin: build, lint, and tests pass.
• api-docs-generator-test-snapshots: build, lint, snapshots, and strict TypeScript diagnostics pass.
• The end-to-end fixture covers ordered declarations, constraints, defaults, nested and cross-module applications, generic inheritance, MSDocs links, changelog changes, and NativeClass<T> synthesis.
• npx beachball check recognizes both package change records.