dev/membership#13 Add handling for missing MembershipPayment record.

dev/membership#13 Add handling for missing MembershipPayment record.

We have an intermittent regression on extending memberships off paypal payments. This adds debug messages
and handling / tests for the scenario I suspect may be in play.

The 'decision' the code makes about how to create recurring transactions is all dependent on the 'template transaction'
- if that is not correct the follow on payments will not be.

This PR allows the membershipID input from paypal to be passed through and used.  This will override any
intended changes - but that just restores previous behaviour and we do not have good handling for these

https://lab.civicrm.org/dev/membership/issues/13