WASAPI: Improve how default devices are created to support automatic stream routing #856

Job	Run time
asmjs-wasm32-test (wasm32-unknown-emscripten)	52s
android-check	37s
cargo-publish	0s
android-apk-build	1m 25s
clippy-test	40s
ios-build	2m 41s
linux-check-and-test-armv7	1m 54s
macos-test	1m 10s
rustfmt-check	5s
ubuntu-test	30s
wasm32-bindgen-test (wasm32-unknown-unknown)	19s
wasm32-wasi-test (wasm32-wasi)	22s
wasm-beep-build	37s
windows-test (x86_64)	3m 42s
windows-test (i686)	3m 1s
	17m 55s

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