add sendfile method for streamsocket (#4007)

* add sendfile method for streamsocket

* add mswsock.lib to the project files and templates

* remove /DPOCO_NO_AUTOMATIC_LIBS for cmake windows build

* merge from upstream

* merge from upstream

* fix code stile
add NotImplemented exception for unsupported platforms
exculude <sys/sendfile.h> for POCO_EMSCRIPTEN, because https://
github.com/emscripten-core/emscripten/pull/16234

* add iostream include for std::cout

* fix compilation for emscripten (wrap sendfile)

Foundation/include/Poco/FileStream.h

@@ -47,6 +47,9 @@ class Foundation_API FileIOS: public virtual std::ios
 	/// On Windows platforms, UTF-8 encoded Unicode paths are correctly handled.
 {
 public:
+
+	using NativeHandle = FileStreamBuf::NativeHandle;
+
 	FileIOS();
 		/// Creates the basic stream.
 
@@ -63,6 +66,12 @@ public:
 	FileStreamBuf* rdbuf();
 		/// Returns a pointer to the underlying streambuf.
 
+	NativeHandle nativeHandle() const;
+		/// Returns native file descriptor handle
+
+	Poco::UInt64 size() const;
+		/// Returns file size
+
 protected:
 	FileStreamBuf _buf;
 };