Fix localization issues, add tests, import translations, and add zh-CN and zh-TW

Closes: #689

damus/Util/LocalizationUtil.swift

@@ -0,0 +1,19 @@
+//
+//  LocalizationUtil.swift
+//  damus
+//
+//  Created by Terry Yiu on 2/24/23.
+//
+
+import Foundation
+
+func bundleForLocale(locale: Locale) -> Bundle {
+    let path = Bundle.main.path(forResource: locale.identifier, ofType: "lproj")
+    return path != nil ? (Bundle(path: path!) ?? Bundle.main) : Bundle.main
+}
+
+func formatInt(_ int: Int) -> String {
+    let numberFormatter = NumberFormatter()
+    numberFormatter.numberStyle = .decimal
+    return numberFormatter.string(from: NSNumber(integerLiteral: int)) ?? "\(int)"
+}

damus/Util/TimeAgo.swift

@@ -50,5 +50,6 @@ public func time_ago_since(_ date: Date, _ calendar: Calendar = Calendar.current
         return formatter.string(from: DateComponents(calendar: calendar, second: second))!
     }
 
-    return NSLocalizedString("now", comment: "String indicating that a given timestamp just occurred")
+    let bundle = bundleForLocale(locale: calendar.locale ?? Locale.current)
+    return NSLocalizedString("now", bundle: bundle, comment: "String indicating that a given timestamp just occurred")
 }