editor: Add Cut, Copy, and Paste actions to the context menu (#11878)

Hi, I saw someone on Twitter mentioned that missing Cut, Copy and Paste
actions in the context menu in the editor block them from using Zed. It
turns out that resolving this issue is simply a matter of adding these
actions to the mouse context menu. To keep items in the context menu
grouped, I placed them at the top of the menu with a separator at the
end. Let me know if that's OK. Thanks!

Here is the screenshot:

![CleanShot 2024-05-16 at 07 04
44@2x](https://github.com/zed-industries/zed/assets/1894248/2ac84001-cdd7-4c01-b597-c5b1dc3e7fa3)

Release Notes:

- Added "Cut", "Copy", and "Paste" actions to the context menu
([#4280](https://github.com/zed-industries/zed/issues/4280)).