Use std::optional if available. (#1630) #2029

Job	Run time
PSV.Linux.22.04.gcc9.Cpplint	9m 7s
PSV.Linux.22.04.gcc9.Tests.CodeCov	10m 49s
PSV.Linux.22.04.gcc9.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	3m 27s
PSV.Linux.Android.22.04	5m 59s
PSV.iOS.MacOS14.Xcode15	7m 9s
PSV.MacOS13.Xcode15.x86_64	3m 17s
PSV.iOS.MacOS15.Xcode16	9m 2s
PSV.MacOS14.Xcode15	3m 47s
PSV.MacOS15.Xcode16	7m 55s
PSV.Win.VC2022	9m 47s
PSV.iOS.MacOS13.Xcode14	13m 22s
PSV.Linux.22.04.gcc11.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	2m 29s
PSV.Linux.latest.gcc14.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	2m 37s
PSV.Linux.22.04.clang	8m 51s
PSV.Linux.22.04.gcc11	8m 22s
PSV.iOS.MacOS13.Xcode15	19m 43s
PSV.Linux.22.04.gcc13	9m 6s
PSV.Clang.Format.Checker	33s
PSV.Commit.Checker	0s
	2h 15m 22s

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