Refactor PartitionsSaxHandler to use boost::json #2228

Job	Run time
PSV.Linux.latest.gcc14.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	2m 31s
PSV.Linux.22.04.gcc11.OLP_SDK_NO_EXCEPTION=ON	7m 3s
PSV.Linux.22.04.gcc9.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	3m 2s
PSV.Linux.22.04.gcc11	8m 44s
PSV.Linux.22.04.gcc9.Cpplint	9m 17s
PSV.Linux.22.04.gcc9.Tests.CodeCov	10m 21s
PSV.Linux.24.04.gcc13.Tests	7m 55s
PSV.Linux.22.04.gcc11.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	2m 37s
PSV.Linux.22.04.clang	9m 58s
PSV.iOS.MacOS15.Xcode16.ARM64	6m 59s
PSV.Commit.Checker	9s
PSV.Clang.Format.Checker	40s
PSV.Linux.Android.22.04	9m 51s
PSV.Win.VC2022	11m 45s
PSV.MacOS15.Xcode16.ARM64	8m 15s
PSV.iOS.MacOS15.Xcode26.ARM64	5m 55s
PSV.iOS.MacOS14.Xcode15.ARM64	5m 33s
	1h 50m 35s

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