Empty() to Blank() or Filled() refactor rule

[peterfox]

Changes

• Adds the RectorLaravel\Rector\Empty_\EmptyToBlankAndFilledFuncRector rule
• Adds a test for the rule.

Why

In the Laravel framework, there are two helpers, blank() and filled(), which are better replacements for PHP's built-in empty() construct, as it has some odd behaviours.

[driftingly]

Thanks @peterfox 🙌