[ci] Download fnm directly from GitHub releases and validate checksum… #119418

Job	Run time
deploy-target	18s
generate-native-matrix	3s
build-wasm (web)	1m 5s
build-wasm (nodejs)	1m 18s
build	2m 59s
stable - aarch64-apple-darwin - node@20	20m 11s
stable - aarch64-pc-windows-msvc - node@20	18m 7s
stable - x86_64-unknown-linux-gnu - node@20	7m 16s
stable - aarch64-unknown-linux-musl - node@20	7m 15s
stable - aarch64-unknown-linux-gnu - node@20	7m 12s
stable - x86_64-pc-windows-msvc - node@20	15m 3s
stable - x86_64-apple-darwin - node@20	18m 34s
stable - x86_64-unknown-linux-musl - node@20	7m 13s
Prepare preview tarball	3m 0s
thank you, build	4s
Upload Turbopack Bytesize metrics to Datadog	11s
Potentially publish release	-1s
	1h 49m 48s

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