Simplify `PieceOffset` #4444

Job	Run time
make-build (ubuntu-latest)	40s
fast-tests (Debug, ubuntu-latest)	1m 3s
make-build (macOS-latest)	44s
long-running-tests (ubuntu-latest, LongRunning)	1m 27s
fast-tests (Debug, windows-latest)	2m 44s
build-and-publish (ubuntu-latest)	47s
long-running-tests (windows-latest, LongRunning)	2m 39s
make-build (macOS-13)	1m 15s
build-and-publish (windows-latest)	1m 48s
fast-tests (Debug, macOS-latest)	1m 11s
long-running-tests (macOS-latest, LongRunning)	1m 59s
build-and-publish (macOS-latest)	47s
fast-tests (Debug, macOS-13)	1m 34s
long-running-tests (macOS-13, LongRunning)	2m 38s
build-and-publish (macOS-13)	1m 6s
fast-tests (Release, ubuntu-latest)	1m 24s
other-tests (ubuntu-latest, Configuration)	38s
fast-tests (Release, windows-latest)	2m 25s
other-tests (windows-latest, Configuration)	1m 32s
fast-tests (Release, macOS-latest)	1m 20s
perft-tests (ubuntu-latest, Perft)	4m 1s
other-tests (macOS-latest, Configuration)	43s
winning-at-chess (ubuntu-latest, WinningAtChess_FixedTime)	2m 33s
fast-tests (Release, macOS-13)	1m 54s
perft-tests (windows-latest, Perft)	5m 2s
other-tests (macOS-13, Configuration)	1m 5s
perft-tests (macOS-latest, Perft)	3m 2s
	48m 1s

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