swift

ba7944b7 - 6.2: Build and install Testing and Foundation for Wasm Swift SDK (#83059)

6.2: Build and install Testing and Foundation for Wasm Swift SDK (#83059) Cherry-pick of #82285, merged as 05204bdf63c1d7e541d68012dd30b96ab52b2bb1 **Explanation**: Include Swift Testing Foundation and libxml2 into the Swift SDK for WebAssembly **Scope**: Limited to Swift SDK for Wasm **Risk**: Low, due to limited scope. Changes were incubated on `main` for 2 weeks with no known issues. Swift Testing changes were incubated for more than a month. **Testing**: Manual testing with Swift SDKs produced off `main`. **Issue**: rdar://155865189 **Reviewer**: @MaxDesiatov --------- Co-authored-by: Yuta Saito <kateinoigakukun@gmail.com>