BridgeJS: Include namespace prefix in ABI names for namespace-nested classes and structs

[krodak]

Overview

ABI names for namespace-nested classes omit the namespace, causing symbol collisions when two namespace enums contain a class with the same bare name. For example, @JS enum Utils { @JS class Converter {} } and @JS enum Formatting { @JS class Converter {} } both produce bjs_Converter_init.

This PR adds an abiName computed property to ExportedClass and ExportedStruct that joins namespace + name with _, then updates all ABI name generation sites to use it.

1. Skeleton model - Added abiName to ExportedClass and ExportedStruct in BridgeJSSkeleton.swift. Returns namespace_name when namespaced, bare name otherwise.

2. SwiftToSkeleton - Constructor, method, static method, and static property ABI names now use abiName from the looked-up class/struct instead of the bare name from the parser state.

3. ExportSwift - Deinit, wrap, and PropertyRenderingContext.className now use abiName.

4. BridgeJSLink - Deinit, wrap, property className, and struct helper Wasm intrinsic names (swift_js_struct_lower_* / swift_js_struct_lift_*) now use abiName.

Before:

bjs_Converter_init, bjs_Converter_deinit, bjs_HTTPServer_call

After:

bjs_Utils_Converter_init, bjs_Utils_Converter_deinit, bjs_Networking_API_HTTPServer_call

5. Collision test - Added @JS enum Formatting { @JS class Converter } alongside @JS enum Utils { @JS class Converter } in the EnumNamespace test input to validate distinct ABI names.

Top-level (non-namespaced) classes and structs are unaffected - abiName falls back to name.