Add common PosixResult and PosixResultValue types

Many services like bsd and nvdrv use these to represent the result
values of functions so add a common type for these as an alternative to
the macros.

app/src/main/cpp/skyline/services/common/result.h

@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: MPL-2.0
+// Copyright © 2021 Skyline Team and Contributors (https://github.com/skyline-emu/)
+
+#pragma once
+
+#include <common.h>
+
+namespace skyline::service {
+    enum class PosixResult : i32 {
+        Success = 0,
+        NotPermitted = 1, // EPERM
+        TryAgain = 11, // EAGAIN
+        Busy = 16, // EBUSY
+        InvalidArgument = 22, // EINVAL
+        InappropriateIoctlForDevice = 25, // ENOTTY
+        NotSupported = 95, // EOPNOTSUPP, ENOTSUP
+        TimedOut = 110, // ETIMEDOUT
+
+    };
+
+    template<typename ValueType>
+    using PosixResultValue = ResultValue<ValueType, PosixResult>;
+}