Allowlist: Add red x to error message

[siljapetasch]

When user wants to add an address to the allowlist that already has a role, an error message is printed. This one is hard to see, so I suggest adding a red X to the message

[arturrez]

please merge latest main and resolve the conflict
once done I should be able to approve it @siljapetasch //cc @felipemadero

[siljapetasch]

@arturrez merged recent changes as requested

[felipemadero]

@siljapetasch hi, thanks for the collaboration. we need all commits to be signed. once that is done, we will merge