Convert JWST ramp fitting step for use with WFI data

[stscijgbot-rstdms]

Issue RCAL-72 was created on JIRA by David Grumm:

This is an evolving list of areas of the JWST ramp fitting step code that should be reviewed and possibly changed:

1. Roman datasets will have only a single integration, so:
   a) eliminate loops over integrations
   b) eliminate calculations of averages (and other statistics) over integrations and the associated output file(s)

2. Multi-processing has recently been added to the JWST ramp fitting; presumably this can left as is for Roman but will need to be verified.

3. The JWST version of ramp fitting expects input to be the jump detection output; it will need to be verified that the code will still work if the jump detection step is skipped.

[stscijgbot-rstdms]

Comment by David Grumm on JIRA:

I have copied a first iteration of utils.py to ███████████████████████████████████████████ I revised the code to handle only a single integration ( "dis-integrating" the code ), which includes reducing the dimensionality of many arrays, and removing code for the integration-specific calculations and their output. This will probably need further revision as I modify the code in the other python files that use these functions in utils.py.