Swift cleanup: remove duplicate or unnecessary initializers using default values

Signed-off-by: Bryan Montz <bryanmontz@me.com>
Signed-off-by: William Casarin <jb55@jb55.com>

damus/Models/Notifications/EventGroup.swift

@@ -18,11 +18,7 @@ class EventGroup {
         return first.created_at
     }
     
-    init() {
-        self.events = []
-    }
-    
-    init(events: [NostrEvent]) {
+    init(events: [NostrEvent] = []) {
         self.events = events
     }
     

damus/Models/Notifications/ZapGroup.swift

@@ -8,9 +8,9 @@
 import Foundation
 
 class ZapGroup {
-    var zaps: [Zapping]
-    var msat_total: Int64
-    var zappers: Set<String>
+    var zaps: [Zapping] = []
+    var msat_total: Int64 = 0
+    var zappers = Set<String>()
     
     var last_event_at: Int64 {
         guard let first = zaps.first else {
@@ -46,12 +46,6 @@ class ZapGroup {
         return grp
     }
     
-    init() {
-        self.zaps = []
-        self.msat_total = 0
-        self.zappers = Set()
-    }
-    
     @discardableResult
     func insert(_ zap: Zapping) -> Bool {
         if !insert_uniq_sorted_zap_by_created(zaps: &zaps, new_zap: zap) {