Add an optional field_id argument to create_field

[as2388]

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[IsaackMwenda]

LGTM. May I check how you have tested this?

[as2388]

LGTM. May I check how you have tested this?

Yes, thanks for checking: I called this function manually against one of our test workspaces, using the field id and string parameters from the problematic cases we encountered when migrating COVID, and tested that:

• The strategy of asking for a label that looks like the field id then updating works.
• Providing an invalid field id causes the script to fail.
• Attempting to create an existing field fails.
  I think that's as much as I can do in test, we can see how it goes when we sync CSAP.