Plottable mccode.dat in NeXus scan case

[willend]

Free-form text area

Please describe what your PR is adding in terms of features or bugfixes:

• Generate mccode.dat by fallback parsing of stdout in NeXus mode.
• Allow plotting mccode.dat without access to any mccode.sim.

Result: Overall behaviour of scan is available in mccode.dat also
in case of single-output mccode.h5 / NeXus.

(All in all a follow-up / extension of #2618)

• Further added mechanism to skip scan-points in case of rumtime failure, functional both in cases where the sim folder is not created (init-time issues) and when a mccode.sim is written but monitor data not.

• Cleaned out references to mcstas.sim (McStas 2.x output)

• Let mcplot (pyqtgraph/matplotlib) spawn both overview plot and NeXus tool if in NeXus + scan mode

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Declaration of use of AI-tools

• Please add a checkmark here if you used AI-tools during the work for this contribution
• Furter, please describe how / where and for what the tools were used:

Claude-assisted:

Prompt1:
When running with the standard 'McCode' output format, the mccode.dat file generated in a scan is populated via reading the underlying 0/ 1/ 2/ ... subfolder datasets.

In NeXus output format however, the underlying data are (intentionally) written to a single HDF5 file instead.

In the NeXus case, please parse the Detector: output from underlying simulations directly from stdout of the simulations instead ( + a copy-pasted stdout output from one step within an mcrun scan)

(Rendered result contained both a mccode.sim and mccode.dat in supplement to mccode.h5 - yet not actually functional with mcplot.)

Prompt 2:
Now look at mcplot - and input file parsing for 'scan' data. It would be nice if there was a fallback-mechanism to plot the content of a mccode.dat without access to mccode.sim and all of the underlying detector files. Could you further finally make an adjustment to NOT create mccode.sim (but still mccode.dat) in the case of a 'NeXus' format scan?

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Development OS / boundary conditions

Please describe what OS you developed and tested your additions on, and if any special dependencies are required:

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PR Checklist for contributing to McStas/McXtrace

For a coherent and useful contribution to McStas/McXtrace, please fill in relevant parts of the checklist:

• My contribution contains something else

  • Explanation is added in free form text above or below the checklist

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[willend]

Test dataset for skip-mechanism (scan "all" cif,lau,laz - some lead to failure)

mcrun -c PSI_DMC.instr --mpi=auto -L -n1e7 --format=NeXus -d Laz_Lau_Cif_scan_NeXus filename=adrenaline.lau,Ag.laz,Al.lau,Al.laz,Al2O3_sapphire.lau,Al2O3_sapphire.laz,alpha_Fe.laz,aspirin.lau,Au.laz,B4C.lau,B4C.laz,Ba.laz,Be.laz,BeO.lau,BeO.laz,Bi.laz,C_diamond.lau,C_graphite.lau,C_graphite.laz,C60.lau,CaF2.lau,Cd.laz,cementite_300K.laz,Cr.laz,Cs.laz,Cu.laz,Cu2MnAl.laz,Fe_Gamma.laz,Fe.laz,Fe2O3.cif,Fe2O3.laz,Fe3O4_mp-19306_computed.cif,Fe3O4_mp-19306_computed.laz,Fe3O4_mp-19306_conventional_standard.cif,Fe3O4.cif,FeOOH.cif,FeOOH.laz,Ga.laz,Gd.laz,Ge.lau,Ge.laz,H2O_ice_1h.laz,He4_hcp.laz,Hg.laz,I2.laz,In.lau,K.laz,leucine.lau,Li.laz,LiF.laz,LiFePO4.lau,Mo.laz,Na2Ca3Al2F14.laz,Nb.laz,Ni.laz,Pb.laz,Pd.laz,Pt.laz,Rb.laz,Se_alpha.laz,Se_beta.laz,Si.laz,SiO2_cristobalite.lau,SiO2_quartza.lau,SiO2_quartza.laz,SiO2_quartzb.lau,SiO2_quartzb.laz,Sn_alpha.laz,Sn_beta.laz,Ti.laz,TiO2_rutile.lau,Tl.laz,UO2.laz,V.lau,V.laz,Y2O3.laz,Y3Fe5O12_YIG.laz,YBaCuO.lau,Zn.laz,Zr.laz

...

Finally [PSI_DMC: Laz_Lau_Cif_scan_NeXus]. Time: 1 [s] 
INFO: Finish running step, get detectors from stdout
INFO: Got detectors
INFO: Write step detectors line into Laz_Lau_Cif_scan_NeXus/mccode.dat
WARNING: 5 of 80 scan point(s) failed or produced no data and were skipped (step indices: 29, 31, 33, 34, 35). Laz_Lau_Cif_scan_NeXus/mccode.dat contains only the 75 successful point(s).
INFO: Placing instr file copy PSI_DMC.instr in dataset Laz_Lau_Cif_scan_NeXus
INFO: Placing generated c-code copy PSI_DMC.c in dataset Laz_Lau_Cif_scan_NeXus