TFP B6 form does not set a "blank" NOGDS field to 0

[s-emerson]

In the IVP and FVP modules, the REDCap forms have a different build for B6 than the TFP module.
The IVP and FVP have the first question (Able to complete / Not able to complete) as a yes/no radio button field with possible values of 0 (Able to complete) or 1 (Not able to complete). However, the TFP has that question as a single radio button field with a possible value of 1 (Not able to complete) and is left blank if the participant was able to complete the form.
The issue is that NACC still expects to see a value of 0 or 1 for the NOGDS field, even though the 0 option is not present on the REDCap form.
The TFP module needs an addition to the "set_to_zero_if_blank" function so that NACC does not interpret that field as missing a value. In the meantime, it must be entered manually within NACC's Working Database.

This issue will be fixed with the upcoming TIP module feature branch.