Simplify OptionalWrapper #823

Job	Run time
Check fmt & build docs	18s
Miri	2m 58s
Minimal versions check (ubuntu-latest)	19s
Build & Test (fancy, 1.70.0, ubuntu-latest)	47s
Minimal versions check (macOS-latest)	29s
Build & Test (fancy, 1.70.0, macOS-latest)	2m 7s
Minimal versions check (windows-latest)	35s
Build & Test (fancy, 1.70.0, windows-latest)	1m 9s
Build & Test (fancy, stable, ubuntu-latest)	49s
Build & Test (fancy, stable, macOS-latest)	1m 57s
Build & Test (fancy, stable, windows-latest)	1m 28s
Build & Test (syntect-highlighter, stable, ubuntu-latest)	49s
Build & Test (syntect-highlighter, stable, macOS-latest)	2m 12s
Build & Test (syntect-highlighter, stable, windows-latest)	1m 52s
	17m 49s

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