Refactor PartitionsSaxHandler to use boost::json #2231

Job	Run time
PSV.Linux.22.04.gcc9.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	3m 20s
PSV.Linux.22.04.gcc9.Cpplint	8m 43s
PSV.Linux.22.04.gcc11	9m 40s
PSV.Linux.22.04.gcc11.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	3m 37s
PSV.Linux.24.04.gcc13.Tests	7m 55s
PSV.Linux.latest.gcc14.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	2m 34s
PSV.Linux.22.04.clang	9m 20s
PSV.Linux.22.04.gcc9.Tests.CodeCov	10m 57s
PSV.iOS.MacOS15.Xcode16.ARM64	9m 25s
PSV.MacOS15.Xcode16.ARM64	4m 37s
PSV.Win.VC2022	10m 24s
PSV.Linux.22.04.gcc11.OLP_SDK_NO_EXCEPTION=ON	7m 25s
PSV.iOS.MacOS15.Xcode26.ARM64	6m 28s
PSV.iOS.MacOS14.Xcode15.ARM64	5m 16s
PSV.Clang.Format.Checker	30s
PSV.Commit.Checker	8s
PSV.Linux.Android.22.04	8m 13s
	1h 48m 32s

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