Merge branch 'optionalConversionTraits' into combined2 #97

Job	Run time
AMD64 Ubuntu 24.04 R 4.4 Force-Tests true	24m 22s
Check minimum supported Arrow C++ Version (19.0.1)	9m 52s
AMD64 Windows C++ RTools 40 ucrt64	26m 41s
rhub/ubuntu-gcc12:latest	48m 10s
AMD64 Windows R release	17m 9s
	2h 6m 14s

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