Use std::optional if available. (#1628) #2023

Job	Run time
PSV.Linux.22.04.gcc9.Cpplint	8m 48s
PSV.Linux.22.04.gcc9.Tests.CodeCov	10m 15s
PSV.Linux.22.04.gcc9.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	2m 41s
PSV.Linux.22.04.gcc11	9m 0s
PSV.Linux.22.04.gcc13	8m 48s
PSV.Linux.22.04.clang	9m 30s
PSV.Commit.Checker	0s
PSV.iOS.MacOS13.Xcode14	13m 43s
PSV.Linux.latest.gcc14.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	2m 37s
PSV.MacOS13.Xcode15.x86_64	4m 38s
PSV.Linux.Android.22.04	5m 35s
PSV.MacOS15.Xcode16	4m 33s
PSV.Win.VC2022	9m 38s
PSV.MacOS14.Xcode15	3m 29s
PSV.Linux.22.04.gcc11.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	3m 4s
PSV.iOS.MacOS14.Xcode15	6m 19s
PSV.iOS.MacOS15.Xcode16	5m 40s
PSV.iOS.MacOS13.Xcode15	18m 17s
PSV.Clang.Format.Checker	28s
	2h 7m 3s

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