[feat] TrailingCommaInMultiLineArrayFixer

|Q            |A  |
|---          |---|
|Bug Fix?     |n  |
|New Feature? |yes|
|BC Breaks?   |n  |
|Deprecations?|n  |
|Tests Pass?  |yes|
|Fixed Tickets|   |
|License      |MIT|
|Doc PR       |   |
                   

This adds the TrailingCommaInMultiLineArrayFixer: PHP Multi-line arrays should have a trailing comma

There is only minor problem that I was unable to resolve, when you have an array like.

```php
<?php

$x = array(
    array());

?>
```

The result will be.

```php
<?php

$x = array(
    array(),);

?>
```

Which is not fully correct, but the detection for this is problamatic.

We can't just add a new line, as that will move the closing brace to the beginging of the line.
And looking for the previous whitespace as something like `($y ? 'yes' : 'no')` will detect the wrong whitespace for indenting.

So we can either detect the missing new-line and add it, and let a nother fixer (or manual change) fix this.
Or leave this as it is now, and try to fix this later using either another fixer or improving this fixer.

Nope, it would not:

```php
if (')' === $token->content || ']' === $token->content) {
    --$bracesLevel;

    if (0 !== $bracesLevel) {
        continue;
    }

    $foundIndex = null;
    $prevToken = $tokens->getTokenNotOfKindSibling($index, -1, array(array(T_WHITESPACE), array(T_COMMENT), array(T_DOC_COMMENT)), $foundIndex);

    if (',' !== $prevToken->content) {
        $tokens->insertAt($foundIndex + 1, array(new Token(',')));
    }

    break;
}
```

The result is the same, but the lookup of the token is done only for the case where you actually need it (i.e. ``0 === $bracesLevel``)