Add a certificate validator hook. (#3069)

* Add a certificate validator hook.

* General tidy up of AppHooks.

* Don't worry about the generic call links.

ElementX/Sources/AppHooks/AppHooks.swift

@@ -0,0 +1,49 @@
+//
+// Copyright 2024 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import Foundation
+
+class AppHooks: AppHooksProtocol {
+    #if IS_MAIN_APP
+    private(set) var appSettingsHook: AppSettingsHookProtocol = DefaultAppSettingsHook()
+    func registerAppSettingsHook(_ hook: AppSettingsHookProtocol) {
+        appSettingsHook = hook
+    }
+    
+    private(set) var bugReportHook: BugReportHookProtocol = DefaultBugReportHook()
+    func registerBugReportHook(_ hook: BugReportHookProtocol) {
+        bugReportHook = hook
+    }
+    
+    private(set) var certificateValidatorHook: CertificateValidatorHookProtocol = DefaultCertificateValidator()
+    func registerCertificateValidatorHook(_ hook: CertificateValidatorHookProtocol) {
+        certificateValidatorHook = hook
+    }
+    #endif
+    
+    private(set) var clientBuilderHook: ClientBuilderHookProtocol = DefaultClientBuilderHook()
+    func registerClientBuilderHook(_ hook: ClientBuilderHookProtocol) {
+        clientBuilderHook = hook
+    }
+}
+
+protocol AppHooksProtocol {
+    func configure()
+}
+
+extension AppHooksProtocol {
+    func configure() { }
+}