Add a "load more" button instead of always inserting events in timelines

Changelog-Added: Add a "load more" button instead of always inserting events in timelines

damus/Views/Timeline/InnerTimelineView.swift

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+//
+//  InnerTimelineView.swift
+//  damus
+//
+//  Created by William Casarin on 2023-02-20.
+//
+
+import SwiftUI
+
+
+struct InnerTimelineView: View {
+    @ObservedObject var events: EventHolder
+    let damus: DamusState
+    let show_friend_icon: Bool
+    let filter: (NostrEvent) -> Bool
+    @State var nav_target: NostrEvent? = nil
+    @State var navigating: Bool = false
+    
+    var MaybeBuildThreadView: some View {
+        Group {
+            if let ev = nav_target {
+                BuildThreadV2View(damus: damus, event_id: (ev.inner_event ?? ev).id)
+            } else {
+                EmptyView()
+            }
+        }
+    }
+    
+    var body: some View {
+        NavigationLink(destination: MaybeBuildThreadView, isActive: $navigating) {
+            EmptyView()
+        }
+        LazyVStack(spacing: 0) {
+            let events = self.events.events
+            if events.isEmpty {
+                EmptyTimelineView()
+            } else {
+                ForEach(events.filter(filter), id: \.id) { (ev: NostrEvent) in
+                    EventView(damus: damus, event: ev, has_action_bar: true)
+                        .onTapGesture {
+                            nav_target = ev
+                            navigating = true
+                        }
+                        .padding(.top, 10)
+                }
+            }
+        }
+        .padding(.horizontal)
+    }
+}
+
+
+struct InnerTimelineView_Previews: PreviewProvider {
+    static var previews: some View {
+        InnerTimelineView(events: test_event_holder, damus: test_damus_state(), show_friend_icon: true, filter: { _ in true }, nav_target: nil, navigating: false)
+            .frame(width: 300, height: 500)
+            .border(Color.red)
+    }
+}

damus/Views/Timeline/LoadMoreButton.swift

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+//
+//  LoadMoreButton.swift
+//  damus
+//
+//  Created by William Casarin on 2023-02-20.
+//
+
+import SwiftUI
+
+struct LoadMoreButton: View {
+    @ObservedObject var events: EventHolder
+    let scroller: ScrollViewProxy?
+    
+    func click() {
+        events.flush()
+        guard let ev = events.events.first, let scroller else {
+            return
+        }
+        scroll_to_event(scroller: scroller, id: ev.id, delay: 0.1, animate: true)
+    }
+    
+    var body: some View {
+        Group {
+            if events.queued > 0 {
+                Button(action: click) {
+                    Text("Load \(events.queued) more")
+                }
+                .font(.system(size: 14, weight: .bold))
+                .padding(10)
+                .frame(height: 30)
+                .foregroundColor(.white)
+                .background(LINEAR_GRADIENT)
+                .clipShape(Capsule())
+            } else {
+                EmptyView()
+            }
+        }
+    }
+}
+
+struct LoadMoreButton_Previews: PreviewProvider {
+    @StateObject static var events: EventHolder = test_event_holder
+    
+    static var previews: some View {
+        LoadMoreButton(events: events, scroller: nil)
+    }
+}
+
+
+let test_event_holder = EventHolder(events: [], incoming: [test_event])