refactor: add Pubkey, Privkey, NoteId string aliases

This is a non-behavioral change in preparation for the actual switchover
from Strings to Ids. The purpose of this kit is to reduce the size of
the switchover commit which is going to be very large.

damus/Views/Onboarding/SuggestedUserView.swift

@@ -8,13 +8,13 @@
 import SwiftUI
 
 struct SuggestedUser: Codable {
-    let pubkey: String
+    let pubkey: Pubkey
     let name: String
     let about: String
     let pfp: URL
     let profile: Profile
 
-    init?(profile: Profile, pubkey: String) {
+    init?(profile: Profile, pubkey: Pubkey) {
 
         guard let name = profile.name,
                 let about = profile.about,
@@ -64,7 +64,7 @@ struct SuggestedUserView_Previews: PreviewProvider {
     static var previews: some View {
         let profile = Profile(name: "klabo", about: "A person who likes nostr a lot and I like to tell people about myself in very long-winded ways that push the limits of UI and almost break things", picture: "https://primal.b-cdn.net/media-cache?s=m&a=1&u=https%3A%2F%2Fpbs.twimg.com%2Fprofile_images%2F1599994711430742017%2F33zLk9Wi_400x400.jpg")
 
-        let user = SuggestedUser(profile: profile, pubkey: "abcd")!
+        let user = SuggestedUser(profile: profile, pubkey: test_pubkey)!
         List {
             SuggestedUserView(user: user, damus_state: test_damus_state())
         }

damus/Views/Onboarding/SuggestedUsersViewModel.swift

@@ -11,7 +11,7 @@ import Combine
 struct SuggestedUserGroup: Identifiable, Codable {
     let id = UUID()
     let title: String
-    let users: [String]
+    let users: [Pubkey]
 
     enum CodingKeys: String, CodingKey {
         case title, users
@@ -34,7 +34,7 @@ class SuggestedUsersViewModel: ObservableObject {
         subscribeToSuggestedProfiles(pubkeys: pubkeys)
     }
 
-    func suggestedUser(pubkey: String) -> SuggestedUser? {
+    func suggestedUser(pubkey: Pubkey) -> SuggestedUser? {
         if let profile = damus_state.profiles.lookup(id: pubkey),
            let user = SuggestedUser(profile: profile, pubkey: pubkey) {
             return user
@@ -42,7 +42,7 @@ class SuggestedUsersViewModel: ObservableObject {
         return nil
     }
 
-    func follow(pubkeys: [String]) {
+    func follow(pubkeys: [Pubkey]) {
         for pubkey in pubkeys {
             notify(.follow(.pubkey(pubkey)))
         }
@@ -66,17 +66,16 @@ class SuggestedUsersViewModel: ObservableObject {
         }
     }
 
-    private func getPubkeys(groups: [SuggestedUserGroup]) -> [String] {
-        var pubkeys: [String] = []
+    private func getPubkeys(groups: [SuggestedUserGroup]) -> [Pubkey] {
+        var pubkeys: [Pubkey] = []
         for group in groups {
             pubkeys.append(contentsOf: group.users)
         }
         return pubkeys
     }
 
-    private func subscribeToSuggestedProfiles(pubkeys: [String]) {
-        let filter = NostrFilter(kinds: [.metadata],
-                                 authors: pubkeys)
+    private func subscribeToSuggestedProfiles(pubkeys: [Pubkey]) {
+        let filter = NostrFilter(kinds: [.metadata], authors: pubkeys)
         damus_state.pool.subscribe(sub_id: sub_id, filters: [filter], handler: handle_event)
     }