Refactor PartitionsSaxHandler to use boost::json #2222

Job	Run time
PSV.Linux.22.04.gcc11.OLP_SDK_NO_EXCEPTION=ON	7m 22s
PSV.Linux.latest.gcc14.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	3m 0s
PSV.Linux.22.04.gcc9.Tests.CodeCov	10m 25s
PSV.Linux.24.04.gcc13.Tests	8m 18s
PSV.iOS.MacOS15.Xcode26.ARM64	8m 47s
PSV.iOS.MacOS15.Xcode16.ARM64	8m 22s
PSV.Linux.22.04.gcc9.Cpplint	9m 27s
PSV.Linux.Android.22.04	8m 23s
PSV.Linux.22.04.gcc11	8m 36s
PSV.Commit.Checker	7s
PSV.Linux.22.04.clang	9m 43s
PSV.Linux.22.04.gcc9.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	3m 5s
PSV.Clang.Format.Checker	40s
PSV.iOS.MacOS14.Xcode15.ARM64	9m 26s
PSV.MacOS15.Xcode16.ARM64	4m 20s
PSV.Win.VC2022	10m 43s
PSV.Linux.22.04.gcc11.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	2m 52s
	1h 53m 36s

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