feat: Add OS version info to user agent for Linux & Windows (#738)

* Add OS versions logic for Linux.

* Delete compiler directives; apple implemented these for us.

---------

Co-authored-by: Chan Yoo <[email protected]>

Author: sichanyoo

Sources/ClientRuntime/Util/PlatformOperationSystemVersion.swift

@@ -5,20 +5,11 @@
 // SPDX-License-Identifier: Apache-2.0
 //
 
-#if os(iOS) || os(watchOS) || os(macOS) || os(tvOS)
-import Foundation.NSProcessInfo
+import class Foundation.ProcessInfo
 
 public struct PlatformOperationSystemVersion {
     static public func operatingSystemVersion() -> String? {
         let osVersion = ProcessInfo.processInfo.operatingSystemVersion
         return "\(osVersion.majorVersion).\(osVersion.minorVersion).\(osVersion.patchVersion)"
     }
 }
-#else
-// TODO: Implement for Linux & Windows
-public struct PlatformOperationSystemVersion {
-    static public func operatingSystemVersion() -> String? {
-        return nil
-    }
-}
-#endif