Add `huak-toolchain` (first-pass) #430

Job	Run time
Clippy lints	2m 50s
Formatting check	29s
Build and test (ubuntu-latest)	5m 13s
Build with maturin	1m 56s
Build and test (windows-latest)	4m 57s
Build and test (macos-latest)	4m 52s
	20m 17s

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