feat: add Sys trait for swapping out system #210

Job	Run time
Rustfmt [Formatter]	16s
cargo-deny	18s
Compile (wasm32-wasip1)	22s
Compile (wasm32-unknown-unknown)	17s
Clippy [Linter] (ubuntu-latest)	15s
Clippy [Linter] (macos-latest)	23s
Compile (x86_64-unknown-linux-musl)	24s
Clippy [Linter] (windows-latest)	43s
Test Suite (windows-latest, 1.70)	1m 7s
Test Suite (ubuntu-latest, 1.70)	16s
Test Suite (ubuntu-latest, stable)	21s
Test Suite (ubuntu-latest, nightly)	19s
Test Suite (macos-latest, 1.70)	27s
Test Suite (windows-latest, stable)	1m 41s
Test Suite (windows-latest, nightly)	1m 3s
Test Suite (macos-latest, stable)	28s
Test Suite (macos-latest, nightly)	29s
	9m 9s

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