Validation error messages are not translatable

[HafizMMoaz]

Every user facing string in the library goes through the Language instance, except the argument and option validation messages, which are built with English string concatenation in Command::validateDefinitions() (src/Command.php:359 and src/Command.php:377):

$errors[] = $label . ' "' . $key . '" is required.';
$errors[] = $label . ' "' . $key . '" must be of type ' . $type . '.';

The $label value (argument / option) is hardcoded English at the call site too.

So running a console in es or pt-br gets translated command listings, help and "command not found", then an English validation error.

Suggested keys, following the existing naming in src/Languages/en/cli.php:

'argument'            => 'argument',
'option'              => 'option',
'validation.required' => '{0} "{1}" is required.',
'validation.type'     => '{0} "{1}" must be of type {2}.',

All three language files need the new keys. A test asserting that en, es and pt-br expose the same key set would stop them drifting, which nothing currently checks.