Add semantic safe API for location notifications (#147)

# Motivation
We want to provide new APIs that are semantically safe when sending location notifications to APNs.

# Modification
The PR adds new types for the location notification and a convenience method to send it notifications with the APNSClient.

# Result
We can now send location notifications.

Author: FranzBusch

Sources/APNSwift/Location/APNSClient+Location.swift

@@ -0,0 +1,50 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the APNSwift open source project
+//
+// Copyright (c) 2022 the APNSwift project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of APNSwift project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import NIOCore
+import Logging
+
+extension APNSClient {
+    /// Sends a location request notification to APNs.
+    ///
+    /// - Parameters:
+    ///   - notification: The notification to send.
+    ///
+    ///   - deviceToken: The hexadecimal bytes that identify the user’s device. Your app receives the bytes for this device token
+    ///    when registering for remote notifications.
+    ///
+    ///   - deadline: Point in time by which sending the notification to APNs must complete.
+    ///
+    ///   - logger: The logger to use for sending this notification.
+    @discardableResult
+    @inlinable
+    func sendLocationNotification(
+        _ notification: APNSLocationNotification,
+        deviceToken: String,
+        deadline: NIODeadline,
+        logger: Logger = _noOpLogger
+    ) async throws -> APNSResponse {
+        try await self.send(
+            // This is just to make the compiler work
+            payload: Int?.none,
+            deviceToken: deviceToken,
+            pushType: .location,
+            expiration: .none, // TODO: Figure out if expiration has any impact here
+            priority: notification.priority,
+            topic: notification.topic,
+            deadline: deadline,
+            logger: logger
+        )
+    }
+}

Sources/APNSwift/Location/APNSLocationNotification.swift

@@ -0,0 +1,74 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the APNSwift open source project
+//
+// Copyright (c) 2022 the APNSwift project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of APNSwift project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import struct Foundation.UUID
+
+/// A location notification.
+public struct APNSLocationNotification {
+    /// A canonical UUID that identifies the notification. If there is an error sending the notification,
+    /// APNs uses this value to identify the notification to your server. The canonical form is 32 lowercase hexadecimal digits,
+    /// displayed in five groups separated by hyphens in the form 8-4-4-4-12. An example UUID is as follows:
+    /// `123e4567-e89b-12d3-a456-42665544000`.
+    ///
+    /// If you omit this, a new UUID is created by APNs and returned in the response.
+    public var apnsID: UUID?
+
+    /// The topic for the notification. In general, the topic is your app’s bundle ID/app ID suffixed with `.location-query`.
+    public var topic: String
+
+    /// The priority of the notification.
+    public var priority: APNSPriority
+
+    /// Initializes a new ``APNSLocationNotification``.
+    ///
+    /// - Important: Your dynamic payload will get encoded to the root of the JSON payload that is send to APNs.
+    /// It is **important** that you do not encode anything with the key `aps`
+    ///
+    /// - Parameters:
+    ///   - priority: The priority of the notification.
+    ///   - appID: Your app’s bundle ID/app ID. This will be suffixed with `.location-query`.
+    ///   - apnsID: A canonical UUID that identifies the notification.
+    @inlinable
+    public init(
+        priority: APNSPriority,
+        appID: String,
+        apnsID: UUID? = nil
+    ) {
+        self.init(
+            priority: priority,
+            topic: appID + ".location-query",
+            apnsID: apnsID
+        )
+    }
+
+    /// Initializes a new ``APNSLocationNotification``.
+    ///
+    /// - Important: Your dynamic payload will get encoded to the root of the JSON payload that is send to APNs.
+    /// It is **important** that you do not encode anything with the key `aps`
+    ///
+    /// - Parameters:
+    ///   - priority: The priority of the notification.
+    ///   - topic: The topic for the notification. In general, the topic is your app’s bundle ID/app ID suffixed with `.location-query`.
+    ///   - apnsID: A canonical UUID that identifies the notification.
+    @inlinable
+    public init(
+        priority: APNSPriority,
+        topic: String,
+        apnsID: UUID? = nil
+    ) {
+        self.priority = priority
+        self.topic = topic
+        self.apnsID = apnsID
+    }
+}