[9.x] Make password rule errors translatable

[reziamini]

Right now, the only way to translate password errors is to set messages into a JSON file.
And we can't use lang/{language}/validation.php in our system to translate error messages.

With this change, we will be able to use PHP files to use translation.

For example, we can change the lang/en/validation.php file into:

return [
    'password' => [
         'mixedCase' => 'The :attribute must contain at least one uppercase and one lowercase letter.',
         'letters' => 'The :attribute must contain at least one letter.',
         'symbols' => 'The :attribute must contain at least one symbol.',
         'numbers' => 'The :attribute must contain at least one number.',
         'uncompromised' => 'The given :attribute has appeared in a data leak. Please choose a different :attribute.',
    ],
];

These changes do not break any old changes, and old users still can use JSON files to translate this message.

If it will be merged, I'll add these messages to lang/en/validation.php in laravel/laravel repo.

And we don't need to create en.json file anymore.