Option to only sync fields on account creation/linking vs every login

Firstly, thank you for the field mapping feature that's recently been introduced. It's great!

One piece that is missing however, is the ability to only synchronize certain fields once (ie. on account creation/linking) instead of every time the user authenticates.

Having that option allows us to have a default set of values from the IDP, and then we can customize them locally as needed.

Thanks again.