Land feature 57's controller work on its release branch

The controller plans config, templates and moved providers' provisions,
hands bus accounts to the vault and judges the new manifest words, on the
feature's SDK and node-engine validator (feature 57, config and provisioning).

internal/inventory/bususers.go

@@ -65,6 +65,9 @@ const (
 	// BusNodeTools is a machine's tool runtime (novox/hq ADR 0175): named like the module it
 	// stands for, recorded as what it is.
 	BusNodeTools = "node-tools"
+	// BusProvisioner is a machine's provisioner client (novox/hq ADR 0349 clause 11, design 57 P3): an account of
+	// its own, named for the machine.
+	BusProvisioner = "provisioner"
 )
 
 // MintBusPassword makes a bus password and records its hash under a username, replacing whatever was