Function ApplyApprovalRulesAsync

Applies the approval rules to a record about to be saved, and says whether this save approves it.

• The save approves when the status becomes Approved and the stored status is not Approved (or the record is new). The approver is the context user and the time is now; the fingerprint is cleared until the caller stamps it from the definition as stored.
• On any other save the three columns keep their stored values (none on a create), so values a client sent are ignored. Moving away from Approved clears nothing: the approval stays as history and stops being current because the status is no longer Approved.

The stored values are read from the database rather than the record's old values, which a client can supply on an update.