Squarespace Contribution improvement

[arborrow]

1. Add address location drop down select to Squarespace Contribution edit blade (default to Home)
2. Enable billing address location for person (and other contact types)
3. If location is home then overwrite address; however, if other type only create or insert over blank data for work, other, and billing.

[arborrow]

For data integrity of SS contributions, it is important to check when merging donations to ensure that no orphans are created (where a ss_contribution.donation_id maps to a deleted donation.donation_id). Merge should check if the donation_id is already used in the ss_contribution table and if so, replace it with the target donation_id (the one that gets merged into).