Update exploit/unix/x11/x11_keyboard_exec to use the x11 libraries

[h00die]

Now that x11 libraries have landed (#18877), updated exploit/unix/x11/x11_keyboard_exec (https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/unix/x11/x11_keyboard_exec.rb) to use them

[github-actions]

Hi!

This issue has been left open with no activity for a while now.

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