Add support for tsp namespaces

[jhendrixMSFT]

The code model has been refactored so that emitted artifacts are tracked in the crate and zero or more sub-modules for that crate. Added module info to adapated types so we can create the correct import statement across modules. This also required updating the Use helper to take a module param during construction.
Improved the detection logic for deleting directories that contain generated code as there can now be multiple directories under src.

Fixes #130

[Copilot]

Pull request overview

This PR implements support for TypeSpec namespaces by mapping them to Rust sub-modules, fundamentally restructuring how generated code is organized within crates. The code model now tracks emitted artifacts in a hierarchical module structure rather than a single flat crate, with each namespace translated to a corresponding sub-module hierarchy.

Changes:

• Refactored code model to support hierarchical module containers (Crate and SubModule types)
• Updated type adaptation to distribute models, enums, unions, and clients across appropriate modules based on their TypeSpec namespace
• Modified import path generation to correctly reference types across module boundaries

Reviewed changes

Copilot reviewed 98 out of 679 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
packages/typespec-rust/src/tcgcadapter/adapter.ts	Adds namespace-to-module mapping logic and distributes types across modules
packages/typespec-rust/src/codemodel/crate.ts	Introduces ModuleContainer type and SubModule class for hierarchical organization
packages/typespec-rust/src/codemodel/types.ts	Adds module field to Model, Enum, and DiscriminatedUnion types
packages/typespec-rust/src/codemodel/client.ts	Adds module field to Client and ResponseHeadersTrait types
packages/typespec-rust/src/codegen/use.ts	Updates import path generation to handle cross-module references
packages/typespec-rust/src/codegen/codeGenerator.ts	Implements recursive code generation for sub-modules
packages/typespec-rust/src/emitter.ts	Updates file writing logic to support nested module directories
packages/typespec-rust/src/utils/utils.ts	Adds buildImportPath utility for constructing qualified import paths
Various test files	Updates test imports to reflect new module structure

[heaths]

A few questions and thoughts, but otherwise LGTM. To note, I'm basing much of this off a previous commit where you prototyped how this looks. Sampling of generated code seems fine, but since I don't know inherently what the TypeSpecs for each of these crates says to do, I can't really judge whether they are correct or not.

That said, the block is because we know Storage isn't right, so we should probably resolve that first. I imagine that will make this PR much smaller and negate having to have a future large PR changing many/most things back to what they should be.