feat: add copy username and password shortcuts

[antoine-amara]

add 2 new keyboard shortcuts in the EntriesList component:

• Ctrl+b to copy the username of the current selected entry
• Ctrl+c to copy the password of the current selected entry

These shortcuts are triggered when the user select an entry. (if the focus is elsewhere it is not available).

Note: I cannot find any code relative to an existing shortcut (Ctrl+b) to copy the password

It resolve the issue on buttercup desktop about missing copy usernme or password shortcuts.

[perry-mitchell]

@antoine-amara Amazing! Thank you..