Refactor Rageshake URL and Target configuration. (#4337)

* Move the rageshakeURL configuration from the BugReportService to AppSettings.

* Refactor Target to return a handle when configuring.

This helps with reconfiguration and removes the @MainActor constraint.

ElementX/Sources/Application/Settings/ConfigurableSetting.swift

@@ -0,0 +1,35 @@
+//
+// Copyright 2025 New Vector Ltd.
+//
+// SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+// Please see LICENSE files in the repository root for full details.
+//
+
+import Combine
+
+/// A setting that can be instantiated with an initial value, overridden and reset back again,
+/// automatically publishing the changes for downstream subscribers to react to.
+///
+/// Unlike ``UserPreference``, this type of setting isn't settable by the user, nor is the
+/// override persisted between app launches.
+struct ConfigurableSetting<T: Equatable> {
+    private let initialValue: T
+    private let subject: CurrentValueSubject<T, Never>
+    var publisher: CurrentValuePublisher<T, Never> { subject.asCurrentValuePublisher() }
+    var isOverridden: Bool { subject.value != initialValue }
+    
+    init(_ initialValue: T) {
+        self.initialValue = initialValue
+        subject = .init(initialValue)
+    }
+    
+    func override(_ value: T) {
+        subject.send(value)
+    }
+    
+    func reset() {
+        if isOverridden {
+            subject.send(initialValue)
+        }
+    }
+}