Create iced_widget subcrate and re-organize the whole codebase

core/src/clipboard.rs

@@ -0,0 +1,23 @@
+//! Access the clipboard.
+
+/// A buffer for short-term storage and transfer within and between
+/// applications.
+pub trait Clipboard {
+    /// Reads the current content of the [`Clipboard`] as text.
+    fn read(&self) -> Option<String>;
+
+    /// Writes the given text contents to the [`Clipboard`].
+    fn write(&mut self, contents: String);
+}
+
+/// A null implementation of the [`Clipboard`] trait.
+#[derive(Debug, Clone, Copy)]
+pub struct Null;
+
+impl Clipboard for Null {
+    fn read(&self) -> Option<String> {
+        None
+    }
+
+    fn write(&mut self, _contents: String) {}
+}