This endpoint finds the user who places an order for the account: its userId or email is the callerInfo to
send when quoting or creating an order. search matches any part of the user's name, login or email; leave it
empty to browse the users of the account. Each user comes with its id, user name, email, phone number and
role. total is the number of matching users: while pageNumber multiplied by pageSize is below total, call
again with pageNumber + 1 to get the next page. Only active users are returned. An unknown accountId returns
a 404.