feat: Parameterize epi_reference_wf to better support rodents

[effigies]

These are changes that are patched in to the epi_reference_wf in SyN-SDC in https://github.com/nipreps/fmriprep-rodents/pull/55/files.

[codecov]

Codecov Report

❌ Patch coverage is 7.69231% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 71.45%. Comparing base (9952f97) to head (1edc94b).

Files with missing lines	Patch %	Lines
niworkflows/workflows/epi/refmap.py	7.69%	12 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #971      +/-   ##
==========================================
- Coverage   71.54%   71.45%   -0.09%     
==========================================
  Files          89       89              
  Lines        8653     8665      +12     
  Branches     1077     1079       +2     
==========================================
+ Hits         6191     6192       +1     
- Misses       2230     2241      +11     
  Partials      232      232              

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