Remove clipboard_windows and simplify modules

src/platform/windows.rs

@@ -0,0 +1,18 @@
+use crate::ClipboardProvider;
+
+use raw_window_handle::HasRawWindowHandle;
+use clipboard_win::{get_clipboard_string, set_clipboard_string};
+use std::error::Error;
+
+pub fn new_clipboard<W: HasRawWindowHandle>(
+    _window: &W,
+) -> Result<Box<dyn ClipboardProvider>, Box<dyn Error>> {
+        Ok(Box::new(clipboard_windows::Clipboard::new()?))
+}
+
+impl ClipboardProvider for clipboard_windows::Clipboard {
+    fn fn read(&self) -> Result<String, Box<dyn Error>> {
+        Ok(get_clipboard_string()?)
+    }
+}
+