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

.github/workflows/test.yml

@@ -12,6 +12,8 @@ jobs:
     - name: Set Environment
       run: sudo xcrun xcode-select -s /Applications/Xcode_26.0.app
     - name: Test Main Packages
-      run: swift test --build-system swiftbuild --package-path Sources/Packages
+      run: xcrun xcodebuild -project Sources/Secretive.xcodeproj -scheme PackageTests test
+      # SPM doesn't seem to pick up on the tests currently?
+      # run: swift test --build-system swiftbuild --package-path Sources/Packages
     - name: Test SecretKit Packages
       run: swift test --build-system swiftbuild