Create a fully-qualified SharedSet resource string.
The resource will be in the following format:
`customers/{customer_id}/sharedSets/{shared_set_id}`
@param customer_id [String] @param shared_set_id [String]
@return [::String]
def shared_set_path customer_id:, shared_set_id:
raise ::ArgumentError, "customer_id cannot contain /" if customer_id.to_s.include? "/"
"customers/#{customer_id}/sharedSets/#{shared_set_id}"
end