Add support for account deletion

As per apple guidelines

Changelog-Added: Added support for account deletion

damus/Util/AccountDeletion.swift

@@ -0,0 +1,22 @@
+//
+//  AccountDeletion.swift
+//  damus
+//
+//  Created by William Casarin on 2023-01-30.
+//
+
+import Foundation
+
+
+func created_deleted_account_profile(keypair: FullKeypair) -> NostrEvent {
+    var profile = Profile()
+    profile.deleted = true
+    profile.about = "account deleted"
+    profile.name = "nobody"
+    
+    let content = encode_json(profile)!
+    let ev = NostrEvent(content: content, pubkey: keypair.pubkey, kind: 0)
+    ev.id = calculate_event_id(ev: ev)
+    ev.sig = sign_event(privkey: keypair.privkey, ev: ev)
+    return ev
+}

damus/Util/Notifications.swift

@@ -95,6 +95,9 @@ extension Notification.Name {
     static var new_unmutes: Notification.Name {
         return Notification.Name("new_unmutes")
     }
+    static var deleted_account: Notification.Name {
+        return Notification.Name("deleted_account")
+    }
 }
 
 func handle_notify(_ name: Notification.Name) -> NotificationCenter.Publisher {