[RF] Use VectorDataStore by default in all RooDataSet constructors

[guitargeek]

There still was a constructor of RooDataSet that was hardcoded to use the TreeDataStore. This needs to be changed, because the RooVectorDataStore is more performant and compatible with the new BatchMode.

This PR also includes some other commits that improve the memory management in the dataset classes with std::unique_ptr.

[phsft-bot]

Starting build on ROOT-debian10-i386/soversion, ROOT-performance-centos8-multicore/cxx17, ROOT-ubuntu18.04/nortcxxmod, ROOT-ubuntu2004/python3, mac1015/cxx17, mac11/cxx14, windows10/cxx14 How to customize builds

[phsft-bot]

Build failed on windows10/cxx14. Running on null:C:\build\workspace\root-pullrequests-build See console output.

Errors:

• [2022-09-22T12:32:47.062Z] LINK : fatal error LNK1104: cannot open file 'C:\build\workspace\root-pullrequests-build\build\bin\libCore.dll' [C:\build\workspace\root-pullrequests-build\build\core\Core.vcxproj]

[phsft-bot]

Build failed on ROOT-performance-centos8-multicore/cxx17. Running on olbdw-01.cern.ch:/data/sftnight/workspace/root-pullrequests-build See console output.

Failing tests:

• projectroot.bindings.pyroot.pythonizations.test.pyunittests_pyroot_roofit_roodataset_numpy

[phsft-bot]

Build failed on ROOT-ubuntu2004/python3. Running on root-ubuntu-2004-1.cern.ch:/home/sftnight/build/workspace/root-pullrequests-build See console output.

Failing tests:

• projectroot.bindings.pyroot.pythonizations.test.pyunittests_pyroot_roofit_roodataset_numpy

[phsft-bot]

Build failed on ROOT-ubuntu18.04/nortcxxmod. Running on sft-ubuntu-1804-2.cern.ch:/build/workspace/root-pullrequests-build See console output.

Failing tests:

• projectroot.bindings.pyroot.pythonizations.test.pyunittests_pyroot_roofit_roodataset_numpy

[phsft-bot]

Build failed on ROOT-debian10-i386/soversion. Running on pcepsft10.dyndns.cern.ch:/build/workspace/root-pullrequests-build See console output.

Failing tests:

• projectroot.bindings.pyroot.pythonizations.test.pyunittests_pyroot_roofit_roodataset_numpy

[phsft-bot]

Build failed on mac11/cxx14. Running on macphsft20.dyndns.cern.ch:/Users/sftnight/build/workspace/root-pullrequests-build See console output.

Failing tests:

• projectroot.bindings.pyroot.pythonizations.test.pyunittests_pyroot_roofit_roodataset_numpy

[phsft-bot]

Starting build on ROOT-debian10-i386/soversion, ROOT-performance-centos8-multicore/cxx17, ROOT-ubuntu18.04/nortcxxmod, ROOT-ubuntu2004/python3, mac1015/cxx17, mac11/cxx14, windows10/cxx14 How to customize builds

[phsft-bot]

Build failed on mac1015/cxx17. Running on macitois21.dyndns.cern.ch:/Users/sftnight/build/workspace/root-pullrequests-build See console output.

Errors:

• [2022-09-22T17:37:33.412Z] CMake Error at /Volumes/HD2/build/workspace/root-pullrequests-build/rootspi/jenkins/root-build.cmake:1088 (message):