Refactor PartitionsSaxHandler to use boost::json #2232

Job	Run time
PSV.Linux.22.04.gcc11	8m 26s
PSV.Linux.22.04.gcc9.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	3m 4s
PSV.Linux.22.04.clang	8m 57s
PSV.MacOS15.Xcode16.ARM64	5m 59s
PSV.iOS.MacOS15.Xcode16.ARM64	7m 16s
PSV.Linux.22.04.gcc9.Cpplint	9m 14s
PSV.Linux.latest.gcc14.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	2m 26s
PSV.Commit.Checker	6s
PSV.iOS.MacOS15.Xcode26.ARM64	6m 43s
PSV.Linux.22.04.gcc11.OLP_SDK_NO_EXCEPTION=ON	7m 21s
PSV.iOS.MacOS14.Xcode15.ARM64	5m 20s
PSV.Linux.Android.22.04	5m 59s
PSV.Linux.22.04.gcc9.Tests.CodeCov	10m 27s
PSV.Linux.22.04.gcc11.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	3m 16s
PSV.Linux.24.04.gcc13.Tests	8m 18s
PSV.Win.VC2022	10m 0s
PSV.Clang.Format.Checker	41s
	1h 43m 33s

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