[REF] Move Self service handlng to shared function to allow for use i…

[seamuslee001]

…n other contribution recur functions

Overview

This moves the selfSerivice function so that it can be used by other ContributionRecur forms

Before

Function on one specfic form

After

Function on shared form

ping @eileenmcnaughton

[civibot]

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[eileenmcnaughton]

straight forward function move - merge on pass