Add no-arg variants of presence operations

I missed these when copying across the public API from JS in 20e7f5f.
The correct behaviour of these variants is not specified by the chat
spec, but this will behaviour will do for now; I’ll think about it a bit
more in #178.

Sources/AblyChat/Presence.swift

@@ -80,8 +80,11 @@ public protocol Presence: AnyObject, Sendable, EmitsDiscontinuities {
     func get(params: PresenceQuery) async throws -> [PresenceMember]
     func isUserPresent(clientID: String) async throws -> Bool
     func enter(data: PresenceData?) async throws
+    func enter() async throws
     func update(data: PresenceData?) async throws
+    func update() async throws
     func leave(data: PresenceData?) async throws
+    func leave() async throws
     func subscribe(event: PresenceEventType, bufferingPolicy: BufferingPolicy) async -> Subscription<PresenceEvent>
     /// Same as calling ``subscribe(event:bufferingPolicy:)`` with ``BufferingPolicy.unbounded``.
     ///
@@ -94,6 +97,20 @@ public protocol Presence: AnyObject, Sendable, EmitsDiscontinuities {
     func subscribe(events: [PresenceEventType]) async -> Subscription<PresenceEvent>
 }
 
+public extension Presence {
+    func enter() async throws {
+        try await enter(data: nil)
+    }
+
+    func update() async throws {
+        try await update(data: nil)
+    }
+
+    func leave() async throws {
+        try await leave(data: nil)
+    }
+}
+
 public extension Presence {
     func subscribe(event: PresenceEventType) async -> Subscription<PresenceEvent> {
         await subscribe(event: event, bufferingPolicy: .unbounded)