Refactor: Testable Keychain and Identity Manager (#584)

* Make static functions instance functions to be testable

* Injectable KeychainManager + Mock + updated tests

* Remove `pendingActions` from identity manager (dead code)

* Remove `getHandshakeState` from identity manager (dead code)

* Remove `getAllSocialIdentities` from identity manager (dead code)

* Remove `getCryptographicIdentity` from identity manager (dead code)

* Remove `resolveIdentity` from identity manager (dead code)

* Identity Manager: minor clean up

* Put Identity Manager behind a protocol

* Remove Keychain and Identity Manager singletons

* Tests: include MockKeychain/MockIdentityManager in project; init identityManager in CommandProcessorTests

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Co-authored-by: jack <jackjackbits@users.noreply.github.com>

bitchat/BitchatApp.swift

@@ -11,7 +11,7 @@ import UserNotifications
 
 @main
 struct BitchatApp: App {
-    @StateObject private var chatViewModel = ChatViewModel()
+    @StateObject private var chatViewModel: ChatViewModel
     #if os(iOS)
     @Environment(\.scenePhase) var scenePhase
     @UIApplicationDelegateAdaptor(AppDelegate.self) var appDelegate
@@ -23,6 +23,14 @@ struct BitchatApp: App {
     #endif
     
     init() {
+        let keychain = KeychainManager()
+        _chatViewModel = StateObject(
+            wrappedValue: ChatViewModel(
+                keychain: keychain,
+                identityManager: SecureIdentityStateManager(keychain)
+            )
+        )
+        
         UNUserNotificationCenter.current().delegate = NotificationDelegate.shared
         // Warm up georelay directory and refresh if stale (once/day)
         GeoRelayDirectory.shared.prefetchIfNeeded()