RF: Deprecate local FreeSurferSource patch (duplicate of NiWorkflows)

[oesteban]

Summary

fmriprep.interfaces.patches.FreeSurferSource (lines 108-117) is an exact duplicate of niworkflows.interfaces.patches.FreeSurferSource.

Both add T2 volume grabbing capability to nipype.interfaces.io.FreeSurferSource with identical code:

class _FSSourceOutputSpec(nio.FSSourceOutputSpec):
    T2 = File(desc='Intensity normalized whole-head volume', loc='mri')

class FreeSurferSource(nio.FreeSurferSource):
    output_spec = _FSSourceOutputSpec

Action items

1. Replace from fmriprep.interfaces.patches import FreeSurferSource with from niworkflows.interfaces.patches import FreeSurferSource in all usage sites (e.g., workflows/bold/registration.py)
2. Deprecate the local copy in fmriprep/interfaces/patches.py
3. Remove after one release cycle

Usage sites

• fmriprep/workflows/bold/registration.py (line 331 in init_bbreg_wf)