Change behavior of class_attributes_separation rule

[paulbalandan]

Description
This PR proposes to change how we use the class_attributes_separation rule. Currently, we only activate changing the separation between class methods to always have a single blank line. This now includes class constants, properties, and trait uses in the picture by using this logic:

1. If the const, property, or trait use has metadata (PHPDoc or Attribute) attached to it, it gets one line.
2. If none, then no blank lines are enforced.
3. If preceding class attribute has metadata while the current has none, there will still be a blank line.

class Foo
{
    /** @var Foo */
    public $bar;
+
    public $baz;
-
    public $qux;
}

4. There are blank lines in between attributes:

class Foo
{
    use FooTrait;
    use BarTrait;
+
    public $bar;
    public $baz;
}

Checklist:

• Securely signed commits
• Conforms to style guide

[kenjis]

I disagree with 2. If none, then no blank lines are enforced.

CI4 classes has a lot of properties, and there are many blank lines.
Blank lines are inserted with some intention (perhaps grouping). Removing empty lines
losts the intention.

Why do you want to remove blank lines?

[paulbalandan]

I tend to agree it may lose the intention. However, some of the spacings are arbitrary, if not useless. I would love to keep the spacing if the intention for doing so is clearly evident in the code (by way of regular comments, perhaps) -- for example, the groupings made in https://github.com/codeigniter4/CodeIgniter4/blob/develop/system/Commands/Generators/Views/model.tpl.php is clear to the intention.

    // Dates
    protected $useTimestamps = false;
    protected $dateFormat    = 'datetime';
    protected $createdField  = 'created_at';
    protected $updatedField  = 'updated_at';
    protected $deletedField  = 'deleted_at';

    // Validation
    protected $validationRules      = [];
    protected $validationMessages   = [];
    protected $skipValidation       = false;
    protected $cleanValidationRules = true;

Otherwise, I'd argue those blank lines adds no value.

[MGatner]

YES! This is great, this one has always bothered me.