Use std::optional if available. #1993

Job	Run time
PSV.Linux.22.04.gcc9.Tests.CodeCov	10m 19s
PSV.Linux.22.04.gcc9.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	3m 4s
PSV.Linux.22.04.gcc9.Cpplint	8m 58s
PSV.Linux.22.04.gcc11	8m 15s
PSV.iOS.MacOS14.Xcode15	5m 27s
PSV.iOS.MacOS13.Xcode14	12m 8s
PSV.MacOS15.Xcode16	7m 7s
PSV.iOS.MacOS15.Xcode16	7m 19s
PSV.iOS.MacOS13.Xcode15	13m 49s
PSV.Linux.Android.22.04	7m 12s
PSV.Clang.Format.Checker	36s
PSV.Linux.22.04.gcc11.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	2m 30s
PSV.Linux.22.04.gcc13	10m 18s
PSV.Linux.latest.gcc14.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	3m 34s
PSV.Commit.Checker	7s
PSV.Linux.22.04.clang	8m 50s
PSV.MacOS13.Xcode15.x86_64	5m 5s
PSV.MacOS14.Xcode15	2m 49s
PSV.Win.VC2022	9m 58s
	2h 7m 25s

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