Add xterm.js in shell command

As we've now added shell command, It would be a nice feature enhancement to access shell in browser. It would be useful when we don't have access to our usual dev environment and would like to access shell of website anyways.

It should be included in admin tools like `example.com/ee-admin/webshell`.

We might need a node server script to handle backend of xterm frontend in browser. A demo is already included in xterm which can be used (mostly) unchanged.

Comece revisando os comandos de shell e as ferramentas administrativas existentes em example.com/ee-admin/webshell; em seguida, inspecione a demonstração do xterm e determine como o script de servidor Node proposto conectaria o terminal do navegador ao shell. O trabalho estará concluído quando houver um shell utilizável no navegador disponível nesse caminho de ferramentas administrativas.

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