Add ignore_initial_volumes param to ConfoundsCorrelationPlot

[tsalo]

Related to nipreps/niworkflows#843.

Changes proposed:

• Add an ignore_initial_volumes parameter to the ConfoundsCorrelationPlot interface.
• Add an ignore_initial_volumes parameter to the confounds_correlation_plot function.

[effigies]

How tough do you think it would be to add a unit test?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (01e9a93) 54.28% compared to head (65f5b01) 57.02%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #83      +/-   ##
==========================================
+ Coverage   54.28%   57.02%   +2.74%     
==========================================
  Files          22       22              
  Lines        2019     2020       +1     
  Branches      391      391              
==========================================
+ Hits         1096     1152      +56     
+ Misses        845      787      -58     
- Partials       78       81       +3     

Flag	Coverage Δ
unittests	57.02% <100.00%> (+2.74%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[tsalo]

I think I can just copy over the unit tests from niworkflows, so probably not too hard. I'll try to do it by EOD.