Create a merchant rule for this customer

#3039. Accountant login only: the service token is refused. Creates a company rule, which outranks a global rule for the same merchant. glAccountCode must be an active account in this customer's chart (422 otherwise); the rule's account name and type are taken from that account. merchantPattern needs at least 3 characters, cannot contain %, _, a backslash or a control character, and cannot consist only of generic words such as fee or payment (422). A pattern and match field another rule of this customer already has is 409. Rows already categorized are not changed; rows still in needs_review with no category are categorized by it on the next sync, and an exact rule with a Revenue target releases that customer's held Stripe revenue on the next posting attempt. Writes an audit_logs row (entity_type merchant_rule, action create).