Make it possible to query by attributes via key-value pairs

[dlh01]

Description

Before:

$blocks = \Alley\WP\match_blocks(
    $post,
    [
        'attrs' => [
            [
                'key'   => 'align',
                'value' => 'right',
            ],
        ],
        'name'  => 'core/paragraph',
    ]
);

After:

$blocks = \Alley\WP\match_blocks(
	$post,
	[
		'attrs' => [
			'align' => 'right',
		],
		'name'  => 'core/paragraph',
	],
);

Use Case

The reason that this syntax isn't supported is so that the attrs parameter behaves like meta_query, tax_query, etc. I still like that consistency, but I also still get annoyed at having to write the whole thing out, so maybe the consistency isn't worth it.