Add server-side validation in BulkRequestSignatures, RequestSignature,
and RequestApproval to load the referenced profiles and verify none
have an ended contract before proceeding. Returns ErrProfileContractEnded
if a profile's contract_end_date is in the past, surfaced as a CONFLICT
GraphQL error in all three resolvers.
Signed-off-by: Sacha Al Himdani <sacha@getprobo.com>
754dac9ec6