[5.3] Fix validator messages for implicit attributes with errors

[themsaid]

In the validations language file you can set a custom attribute name for implicit attributes:

'attributes' => [
    'image.*' => 'Images'
],

This would replace the attribute name for all image errors with Images and will produce messages like "Images is required" instead of "image.0 is required".

You can also have this:

'attributes' => [
    'image.1' => 'Images'
],

Which will replace only image.1 with "Images" keeping the rest of the messages to be displayed as is.

The problem is that the validator uses $this->trans('validations.attributes.image.1') which expects a format like this:

'attributes' => [
    'image' => ['1' => 'Images']
],

Internally trans() uses Arr:get() which searches for the key using the dot format.

However, Arr:get() checks for the exact key first before assuming it's in dot format so calling Arr::get($attributes, 'image.1') will check for exact key image.1 before checking for ['image'][1], for this Instead of calling $this->trans('validations.attributes.image.1') I collect all attributes translations using $this->trans->get('validation.attributes') and then use array get to get the keys.

That's the main purpose of the PR, however in the Validator test we use Symfony's translator instead of Laravel's translator because it contains an AddResource method we use in tests, but passing Symfony's translator while we use Translator::get() method, which only exists in Laravel's, throws an exception.

So in this PR I added an addLines() method to Laravel's translator and converted the tests to use Laravel's translator and this method instead of Symfony's.