build: add clippy lints (#546) #1854

Job	Run time
Check	1m 27s
Test C++ Runtime (ubuntu-latest)	3m 38s
Test C++ Runtime (windows-latest)	6m 9s
Test mdbook	52s
Test C++ Runtime (macOS-latest)	10m 12s
Doctest Rust (ubuntu-latest)	1m 21s
Doctest Rust (windows-latest)	3m 49s
Doctest Rust (macOS-latest)	2m 31s
Check Style	1m 43s
Test Rust (ubuntu-latest)	4m 2s
Test Rust (windows-latest)	8m 50s
Test Rust (macOS-latest)	6m 28s
	51m 2s

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