Configure what fields are PII for VS export

[jpye-finch]

Description

As part of form configuration. A developer needs to configure what fields are PII and thus not be exported in Vital Statistics Export

Acceptance criteria

GIVEN I configuring the birth, death and marriage form
WHEN adding a field
THEN i can set 'containsPII' as TRUE

GIVEN I and exporting birth, death or marriage VS
THEN I only fields where 'containsPII' as FALSE are exported

Dev tasks

• Task 1

[rikukissa]

Best to delay this until we’ve gotten our data in order. Currently there is no trivial way to connect the form configuration with the data we've stored in our database. We can prioritise this if there’s a direct country requirement.

[jpye-finch]

Linked #6212
#6261
#6948