build: add clippy lints #1851

Job	Run time
Check	1m 19s
Test Rust (ubuntu-latest)	4m 20s
Test Rust (windows-latest)	10m 15s
Test mdbook	47s
Test C++ Runtime (ubuntu-latest)	3m 53s
Test Rust (macOS-latest)	4m 40s
Doctest Rust (ubuntu-latest)	1m 23s
Test C++ Runtime (windows-latest)	7m 58s
Doctest Rust (windows-latest)	4m 37s
Test C++ Runtime (macOS-latest)	5m 58s
Doctest Rust (macOS-latest)	2m 10s
Check Style	1m 24s
	48m 44s

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