Messenger example - send auth request

• Refactor user search
• Add contact feature
• Save found contacts
• Add send request feature
• Send auth request
• Fix saving my contact during registration

Examples/xx-messenger/Sources/AppCore/XXClientHelpers/FactHelpers.swift

+import XXClient
+
+// TODO: Move to XXClient library
+
+public enum FactType: Equatable {
+  case username
+  case email
+  case phone
+  case other(Int)
+
+  public static let knownTypes: [Self] = [.username, .email, .phone]
+
+  public init(rawValue: Int) {
+    if let known = FactType.knownTypes.first(where: { $0.rawValue == rawValue }) {
+      self = known
+    } else {
+      self = .other(rawValue)
+    }
+  }
+
+  public var rawValue: Int {
+    switch self {
+    case .username: return 0
+    case .email: return 1
+    case .phone: return 2
+    case .other(let rawValue): return rawValue
+    }
+  }
+}
+
+extension Array where Element == Fact {
+  public func get(_ type: FactType) -> Fact? {
+    first(where: { $0.type == type.rawValue })
+  }
+
+  public mutating func set(_ type: FactType, _ value: String?) {
+    removeAll(where: { $0.type == type.rawValue })
+    if let value = value {
+      append(Fact(fact: value, type: type.rawValue))
+      sort(by: { $0.type < $1.type })
+    }
+  }
+}
+
+extension Contact {
+  public func getFact(_ type: FactType) throws -> Fact? {
+    try getFacts().get(type)
+  }
+
+  public mutating func setFact(_ type: FactType, _ value: String?) throws {
+    var facts = try getFacts()
+    facts.set(type, value)
+    try setFacts(facts)
+  }
+}