Date of final state change

[jpmckinney]

Splitting from #1160

Copying some discussion from CRM-8486.

A publisher wants to disclose the date on which the process reached its final state. This date might differ from the date on which the notice is published (date).

We can either have:

1. One field for each state (dateCancelled and dateWithdrawn – presumably, dateUnsuccessful is not needed, as this occurs simultaneously with the tenderPeriod/endDate if there are no qualified bids)
2. One field for the final state (since the final states are disjoint – i.e. a process can't be both cancelled and withdrawn, etc. – we only ever have one date to model). The field name would follow whatever name we choose for the status.

I would go with 2.

[duncandewhurst]

To be done at the same time as #1583. Blocked until #1160 is done.

[jpmckinney]

Unblocked

[odscjen]

Based on the advice given in the CRM issue, which was taking into account the new finalStatus fields in 1.2, we should use finalStatusDate as the single field name, an use this in every object that has a finalStatus field.