tidy_exwas_outcomes: Tidy the outcomes of regression run on a mids object
In groovearmada/exwas:

Tidy the outcomes of regression run on a mids object, so they can be used for plotting and exported as .csv table

1	tidy_exwas_outcomes(model, subcohort, file_name)

`model`	Regression output
`subcohort`	A one element character vector indicating a stratification factor
`file_name`	Path and file name (to which .csv or _plot.csv will be added)

##---- Should be DIRECTLY executable !! ----
##-- ==>  Define data, use random,
##--	or do  help(data=index)  for the standard data sets.

## The function is currently defined as
function (x)
{
  }