Refactor PartitionsSaxHandler to use boost::json #2224

Job	Run time
PSV.Linux.22.04.gcc11.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	3m 22s
PSV.Linux.22.04.gcc11.OLP_SDK_NO_EXCEPTION=ON	7m 18s
PSV.iOS.MacOS15.Xcode26.ARM64	7m 51s
PSV.Linux.latest.gcc14.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	2m 48s
PSV.Linux.22.04.gcc9.Cpplint	9m 9s
PSV.iOS.MacOS15.Xcode16.ARM64	6m 28s
PSV.Linux.22.04.clang	8m 56s
PSV.Linux.22.04.gcc9.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	3m 24s
PSV.Win.VC2022	10m 19s
PSV.Linux.22.04.gcc11	8m 31s
PSV.Linux.Android.22.04	6m 1s
PSV.Linux.24.04.gcc13.Tests	7m 54s
PSV.MacOS15.Xcode16.ARM64	5m 12s
PSV.Linux.22.04.gcc9.Tests.CodeCov	11m 21s
PSV.Commit.Checker	5s
PSV.Clang.Format.Checker	32s
PSV.iOS.MacOS14.Xcode15.ARM64	5m 39s
	1h 44m 50s

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