Drop Runtime::spawn in favor of spawn_cancellable_background_task

We now drop the generic `spawn` from our internal `Runtime` API,
ensuring we'd always have to either use
`spawn_cancellable_background_task` or `spawn_background_task`.

Author: tnull

src/event.rs

@@ -1059,7 +1059,7 @@ where
 					forwarding_channel_manager.process_pending_htlc_forwards();
 				};
 
-				self.runtime.spawn(future);
+				self.runtime.spawn_cancellable_background_task(future);
 			},
 			LdkEvent::SpendableOutputs { outputs, channel_id } => {
 				match self.output_sweeper.track_spendable_outputs(outputs, channel_id, true, None) {
@@ -1441,7 +1441,7 @@ where
 						}
 					}
 				};
-				self.runtime.spawn(future);
+				self.runtime.spawn_cancellable_background_task(future);
 			},
 			LdkEvent::BumpTransaction(bte) => {
 				match bte {

src/gossip.rs

@@ -144,6 +144,6 @@ impl RuntimeSpawner {
 
 impl FutureSpawner for RuntimeSpawner {
 	fn spawn<T: Future<Output = ()> + Send + 'static>(&self, future: T) {
-		self.runtime.spawn(future);
+		self.runtime.spawn_cancellable_background_task(future);
 	}
 }

src/runtime.rs

@@ -61,15 +61,6 @@ impl Runtime {
 		}
 	}
 
-	pub fn spawn<F>(&self, future: F) -> JoinHandle<F::Output>
-	where
-		F: Future + Send + 'static,
-		F::Output: Send + 'static,
-	{
-		let handle = self.handle();
-		handle.spawn(future)
-	}
-
 	pub fn spawn_background_task<F>(&self, future: F)
 	where
 		F: Future<Output = ()> + Send + 'static,