chore: fixes for php-cs-fixer and psalm

[paulbalandan]

Description
I have included manual fixes, too.

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value (without duplication)
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[neznaika0]

A small clarification - would a type without a variable be a serious violation? Or the opposite case - is it worth removing the variable if @var refers to the next line?

/** @var int $a */
$a = 123;
/** @var int */
$b = 456;

[paulbalandan]

I'm not sure. It seems IDEs can still understand if the var name is omitted. Personally, I go with specifying the var name explicitly.