List Client Linkable CIS Organisations

The CIS Manager organisations the signed-in user already has that the client could be linked to instead of creating one: those the practice runs that they can open, and their own in no practice, leaving out any linked to a client. Best match for the client's PAYE and Accounts Office references, UTR and name first. Empty when the client is linked already, the practice is not connected to CIS Manager, or the user has not joined the practice there yet.

Requires: Create on ProductAccounts.