contractcourt: remove the immediate param used in Resolve

This `immediate` flag was added as a hack so during a restart, the
pending resolvers would offer the inputs to the sweeper and ask it to
sweep them immediately. This is no longer need due to `blockbeat`, as
now during restart, a block is always sent to all subsystems via the
flow `ChainArb` -> `ChannelArb` -> resolvers -> sweeper. Thus, when
there are pending inputs offered, they will be processed by the sweeper
immediately.

contractcourt/contract_resolver.go

@@ -42,7 +42,7 @@ type ContractResolver interface {
 	// resolution, then another resolve is returned.
 	//
 	// NOTE: This function MUST be run as a goroutine.
-	Resolve(immediate bool) (ContractResolver, error)
+	Resolve() (ContractResolver, error)
 
 	// SupplementState allows the user of a ContractResolver to supplement
 	// it with state required for the proper resolution of a contract.