Add a binding for exiting the diff view

**Is your feature request related to a problem? Please describe.**
Currently, we can use `l` to enter the diff view, but not `h` to exit it.

**Describe the solution you'd like**
As titled

**Describe alternatives you've considered**
None

**Additional context**
None

Empieza localizando el binding `l` existente que entra en la vista de diff y el handler de la vista de diff. Añade el binding `h` correspondiente para salir de la vista y, después, ejecuta la prueba relevante o verifica manualmente el comportamiento de la tecla en la UI de terminal.

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