fix KDSource visualization

[jorobledo]

Trace in McStas was not really possible because we could not subsample the set of ray counts. This PR just allows to NOT overwrite the ncount when we do trace, and then just trace the number passed in -n. Allows for KDS component visualization in mcdisplay.

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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:

Nope

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Development OS / boundary conditions

Tested on Mac

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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 includes patches to an existing component file

  • [ x ] I have used the mcdoc utility and rendered a reasonable documentation page for the component (please attach as screenshot in comments!)
  • [ x ] I have ensured that basic use of the component is OK (e.g. an instrument using it compiles?)
  • [ x ] I have used the mctest utility to test one or more instruments making use of the component (please attach mcviewtest report as screenshot in comments)

Compiling instruments [seconds]...
Test_KDSource :   1.48

Running tests / getting status...
Test_KDSource  :   Display OK (1s)
Test_KDSource  :   0.87    [val: 3996.61 / 4056.0 = 99 %]
 - Test 1 plots generated OK
Test_KDSource_2:   0.75    [val: 4002.57 / 4056.0 = 99 %]
 - Test 2 plots generated OK
Test_KDSource_3:   3.06    [val: 4005.7 / 4056.0 = 99 %]
 - Test 3 plots generated OK
Test_KDSource_4:  26.21    [val: 4002.88 / 4056.0 = 99 %]
 - Test 4 plots generated OK
======================================
Overall test result:
SUCCESS

• [ ] I have used the mccode-clangformat tool to apply the standard McCode component indentation scheme
• I have used the mcrun --c-lint "linter" and followed advice to remove most / all warnings that are raised

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[willend]

@jorobledo great, just like we discussed. Maybe we should in fact do the same fix for MCPL_input*.comp

[jorobledo]

tests for the MCPL_input* components fix.

Compiling instruments [seconds]...
Test_MCPL_input      :   3.51
Test_MCPL_input_once :   3.14

Running tests / getting status...
Test_MCPL_input       :   Display OK (2s)
Test_MCPL_input       :   1.07    [val: 227516000000.0 / 242284000000.0 = 94 %]
 - Test 1 plots generated OK
Test_MCPL_input_2     :   1.16    [val: 227516000000.0 / 242284000000.0 = 94 %]
 - Test 2 plots generated OK
Test_MCPL_input_once  :   Display OK (1s)
Test_MCPL_input_once  :   1.04    [val: 227516000000.0 / 242284000000.0 = 94 %]
 - Test 1 plots generated OK
Test_MCPL_input_once_2:   1.05    [val: 227516000000.0 / 242284000000.0 = 94 %]
 - Test 2 plots generated OK
======================================
Overall test result:
SUCCESS