highlight: fixes and improvements

This patch allows highlights to be included in posts as well as removes context
when creating a highlight. Highlights now route as the root and selecting the
highlight in root routes to the highlighted event.

Signed-off-by: ericholguin <ericholguin@apache.org>

damus/Models/ContentFilters.swift

@@ -16,7 +16,7 @@ enum FilterState : Int {
     func filter(ev: NostrEvent) -> Bool {
         switch self {
         case .posts:
-            return ev.known_kind == .boost || !ev.is_reply()
+            return ev.known_kind == .boost || ev.known_kind == .highlight || !ev.is_reply()
         case .posts_and_replies:
             return true
         }

damus/Models/ThreadModel.swift

@@ -11,13 +11,15 @@ import Foundation
 class ThreadModel: ObservableObject {
     @Published var event: NostrEvent
     let original_event: NostrEvent
+    let highlight: String?
     var event_map: Set<NostrEvent>
     
-    init(event: NostrEvent, damus_state: DamusState) {
+    init(event: NostrEvent, damus_state: DamusState, highlight: String? = nil) {
         self.damus_state = damus_state
         self.event_map = Set()
         self.event = event
         self.original_event = event
+        self.highlight = highlight
         add_event(event, keypair: damus_state.keypair)
     }