User tagging and autocompletion

Co-authored-by: William Casarin <jb55@jb55.com>
Changelog-Added: User tagging and autocompletion in posts
Closes: #347
Fixes: #411, #63

damus/ContentView.swift

@@ -302,7 +302,7 @@ struct ContentView: View {
             case .report(let target):
                 MaybeReportView(target: target)
             case .post:
-                PostView(replying_to: nil, references: [])
+                PostView(replying_to: nil, references: [], damus_state: damus_state!)
             case .reply(let event):
                 ReplyView(replying_to: event, damus: damus_state!)
             }