Add default bindings for the "copy" and "paste" keyboard keys.

These keys are present in some old unix keyboards, but more importantly,
their keycodes can be mapped to physical keys in modern programmable
keyboards.
Using them in Linux is a way to be able to have the same keys for
copy/pasting in GUI apps and in terminal apps instead of switching between
ctrl-c/ctrl-v and ctrl-shift-c/ctrl-shift-v.

src/config/Config.zig

@@ -5564,6 +5564,17 @@ pub const Keybinds = struct {
         );
 
         {
+            try self.set.put(
+                alloc,
+                .{ .key = .{ .physical = .copy } },
+                .{ .copy_to_clipboard = {} },
+            );
+            try self.set.put(
+                alloc,
+                .{ .key = .{ .physical = .paste } },
+                .{ .paste_from_clipboard = {} },
+            );
+
             // On non-MacOS desktop envs (Windows, KDE, Gnome, Xfce), ctrl+insert is an
             // alt keybinding for Copy and shift+ins is an alt keybinding for Paste
             //