Filter displayed items by selected organization

When operator is looking at anything, it should only show items that belong to the orgs Operator selected. 

Under an operator's org filter, Brains now lists only the selected orgs' accounts plus accounts shared with them, each labelled with its org. Counters follow the filter. The Customers and Billing orgs rosters filter too. Quick gate green; review and security findings fixed; visual check OK. PR #6730 merged (244579d); its deploy was superseded by a newer one. Memory: none applied.