Improve NostrNetworkManager interfaces

This commit improves NostrNetworkManager interfaces to be easier to use,
and with more options on how to read data from the Nostr network

This reduces the amount of duplicate logic in handling streams, and also
prevents possible common mistakes when using the standard subscribe method.

This fixes an issue with the mute list manager (which prompted for this
interface improvement, as the root cause is similar to other similar
issues).

Closes: https://github.com/damus-io/damus/issues/3221
Signed-off-by: Daniel D’Aquino <daniel@daquino.me>

damusTests/NostrNetworkManagerTests/NostrNetworkManagerTests.swift

@@ -47,8 +47,8 @@ class NostrNetworkManagerTests: XCTestCase {
         Task {
             for await item in self.damusState!.nostrNetwork.reader.subscribe(filters: [filter]) {
                 switch item {
-                case .event(borrow: let borrow):
-                    try? borrow { event in
+                case .event(let lender):
+                    try? lender.borrow { event in
                         receivedCount += 1
                         if eventIds.contains(event.id) {
                             XCTFail("Got duplicate event ID: \(event.id) ")