ENH: Create a crashfile even if 'stop_on_first_crash' is set

[chrisgorgo]

This makes error reporting more consistent and helps building apps (such as fmriprep) on top of nipype.

[codecov-io]

Codecov Report

Merging #2774 into master will decrease coverage by 0.02%.
The diff coverage is 33.33%.

@@            Coverage Diff             @@
##           master    #2774      +/-   ##
==========================================
- Coverage    67.5%   67.48%   -0.03%     
==========================================
  Files         340      340              
  Lines       43271    43271              
  Branches     5364     5364              
==========================================
- Hits        29210    29201       -9     
- Misses      13360    13368       +8     
- Partials      701      702       +1

Flag	Coverage Δ
#smoketests	50.6% <0%> (ø)	⬆️
#unittests	64.88% <33.33%> (-0.04%)	⬇️

Impacted Files	Coverage Δ
nipype/pipeline/plugins/linear.py	88.57% <0%> (ø)	⬆️
nipype/pipeline/plugins/base.py	59.55% <100%> (ø)	⬆️
nipype/pipeline/plugins/legacymultiproc.py	60.5% <0%> (-4.5%)	⬇️

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