Move downloader and socket input parsing to xpc services (#675)

* XPC updater POC

* WIP

* obo

* WIP

* Working

* .

* .

* .

* Cleanup

* Cleanup

* Throw restrict

* Remove dead protocol.

* .

* Fix ECDSA test.

* Scripts

Sources/ReleasesDownloader/Info.plist

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>XPCService</key>
+	<dict>
+		<key>ServiceType</key>
+		<string>Application</string>
+	</dict>
+</dict>
+</plist>

Sources/ReleasesDownloader/main.swift

@@ -0,0 +1,44 @@
+import XPC
+import OSLog
+import Brief
+
+private let logger = Logger(subsystem: "com.maxgoedjen.secretive.ReleasesDownloader", category: "ReleasesDownloader")
+
+enum Constants {
+    static let updateURL = URL(string: "https://api.github.com/repos/maxgoedjen/secretive/releases")!
+}
+
+func handleRequest(_ request: XPCListener.IncomingSessionRequest) -> XPCListener.IncomingSessionRequest.Decision {
+    logger.log("ReleasesDownloader received inbound request")
+    return request.accept { xpcDictionary in
+        xpcDictionary.handoffReply(to: .global(qos: .userInteractive)) {
+            logger.log("ReleasesDownloader accepted inbound request")
+            Task {
+                do {
+                    let (data, _) = try await URLSession.shared.data(from: Constants.updateURL)
+                    let releases = try JSONDecoder().decode([Release].self, from: data)
+                    xpcDictionary.reply(releases)
+                } catch {
+                    logger.error("ReleasesDownloader failed with unknown error \(error)")
+                    xpcDictionary.reply([] as [Release])
+                }
+            }
+        }
+    }
+}
+
+do {
+    if #available(macOS 26.0, *) {
+        _ = try XPCListener(
+            service: "com.maxgoedjen.Secretive.ReleasesDownloader",
+            requirement: .isFromSameTeam(),
+            incomingSessionHandler: handleRequest(_:)
+        )
+    } else {
+        _ = try XPCListener(service: "com.maxgoedjen.Secretive.ReleasesDownloader", incomingSessionHandler: handleRequest(_:))
+    }
+    logger.log("ReleasesDownloader initialized")
+    dispatchMain()
+} catch {
+    logger.error("Failed to create ReleasesDownloader, error: \(error)")
+}