Add assertStructuredContent method

[gdebrauwer]

There is currently no way to assert the structured content of a tool response. This PR fixes that.

$response = BookingServer::tool(GetBookingTool::class);

$response->assertStructuredContent([
	'type' => 'booking',
	'id' => 123,
	'status' => 'confirmed',
]);

[pushpak1300]

Can you fix static analysis issue ?