Refactor PartitionsSaxHandler to use boost::json #2221

Job	Run time
PSV.Linux.22.04.gcc11	9m 1s
PSV.Linux.22.04.gcc9.Tests.CodeCov	10m 26s
PSV.Linux.22.04.gcc9.Cpplint	9m 41s
PSV.Linux.22.04.gcc11.OLP_SDK_NO_EXCEPTION=ON	3m 17s
PSV.Linux.24.04.gcc13.Tests	8m 26s
PSV.Linux.latest.gcc14.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	2m 29s
PSV.Win.VC2022	7m 30s
PSV.Linux.22.04.gcc9.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	3m 17s
PSV.Commit.Checker	7s
PSV.iOS.MacOS15.Xcode16.ARM64	6m 26s
PSV.Linux.22.04.clang	3m 13s
PSV.iOS.MacOS14.Xcode15.ARM64	4m 29s
PSV.Linux.22.04.gcc11.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	2m 47s
PSV.Clang.Format.Checker	34s
PSV.iOS.MacOS15.Xcode26.ARM64	5m 14s
PSV.Linux.Android.22.04	3m 56s
PSV.MacOS15.Xcode16.ARM64	6m 52s
	1h 27m 45s

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