MySqliDriver: Do not close connection when initialized with a resource (side effect)

[dakujem]

This is a feature request or an edge-case bug report.

MySqliDriver closes the connection upon destruction of its parent Connection object:
Connection::__destruct ⟶ Connection::disconnect ⟶ MySqliDriver::disconnect (code here) ⟶ \mysqli::close

In a scenario like the following this behaviour will cause an error.

$container['database'] = new \mysqli($cfg['host'], $cfg['username'], $cfg['password'], $cfg['database']);

function doSomething(\mysqli $connection) {
    $dibi = new Connection(config: [
        'resource' => $connection,
        'driver' => 'mysqli',
    ]);
    $dibi->query(...);
    return;
    // at this point the $dibi variable goes out of scope and is destructed
}

/** @var \mysqli $db */
$db = $container->get('database');

// side-effect here, the DB disconnects after this function returns
doSomething($db);

// and then... oops!
$db->query(...); // Error: mysqli object is already closed

Even though this is an edge case, the scenario should be supported.
PdoDriver::disconnect() does not do this, it simply nulls the connection; I haven ot checked the other drivers.

Suggested solution

I suggest something like this:

// MySqliDriver
public function disconnect(): void {
    !$this->initializedWithResource && @$this->connection->close(); 
}

... and adding $this->initializedWithResource = true in the constructor here.

I am able to provide a PR.

P.S. I haven't tested or encountered this, but I noticed this possibility when working on #410