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/SearchResultsView.swift

@@ -15,8 +15,8 @@ struct MultiSearch {
 enum Search: Identifiable {
     case profiles([SearchedUser])
     case hashtag(String)
-    case profile(String)
-    case note(String)
+    case profile(Pubkey)
+    case note(NoteId)
     case nip05(String)
     case hex(String)
     case multi(MultiSearch)
@@ -38,7 +38,7 @@ struct InnerSearchResults: View {
     let damus_state: DamusState
     let search: Search?
     
-    func ProfileSearchResult(pk: String) -> some View {
+    func ProfileSearchResult(pk: Pubkey) -> some View {
         FollowUserView(target: .pubkey(pk), damus_state: damus_state)
     }