Replace sdcflows calls with dependency calls

[tsalo]

Closes None, but works toward #199.

I think the adapted version is from 1.3.3.

The elements from sdcflows that aslprep uses are:

• fieldmap_wrangler
• init_sdc_estimate_wf
• init_sdc_unwarp_report_wf

Unfortunately, sdcflows has changed considerably since the code was copied into aslprep, and fmriprep's field map handling is really complex.

Changes proposed in this pull request

Documentation that should be reviewed

[tsalo]

I think the sdcflows and niworkflows versions conflict, since the failure happens within sdcflows.

[tsalo]

Closing in favor of #338.