Fix ArrayHelper::filter for filters with keys for non-array values + refactoring tests

[vjik]

Q	A
Is bugfix?	✔️
New feature?	❌
Breaks BC?	❌
Fixed issues	-

Fixed error:

ArrayHelper::filter(
	[
		'A' => [
			'B' => 1,
			'C' => 2,
			'D' => [
				'E' => 1,
				'F' => 2,
			],
		],
		'G' => 1,
	],
	['A.B.X']
);

A.B is not array and throws exception.

[samdark]

👍