Using --format=html while debugging unit tests with $this->json(...$args)->dump(); throws exception

Simillar to #9 (I guess?) I'm getting an exception while running unit test and try to debug a request with the `->dump()` helper, such as
```php
class CategoryModuleTest extends TestCase
{
public function testAdminCanAccessCategoriesModule()
{
$this->signIn(Admin::first());

$this->json('GET', route('web.api.lists.categories.index'))
->dump()
->assertOk()
->assertJsonCount(1, 'meta.order');
}
}
```

```
Symfony\Component\Debug\Exception\FatalThrowableError : Argument 1 passed to Symfony\Component\VarDumper\Dumper\HtmlDumper::dump() must be an instance of Symfony\Component\VarDumper\Cloner\Data, null given, called in C:\path\to\project\vendor\symfony\var-dumper\Command\Descriptor\HtmlDescriptor.php on line 47
--
  |  
  | at C:\path\to\project\vendor\symfony\var-dumper\Dumper\HtmlDumper.php:111
  | 107\|
  | 108\| /**
  | 109\| * {@inheritdoc}
  | 110\| */
  | > 111\| public function dump(Data $data, $output = null, array $extraDisplayOptions = array())
  | 112\| {
  | 113\| $this->extraDisplayOptions = $extraDisplayOptions;
  | 114\| $result = parent::dump($data, $output);
  | 115\| $this->dumpId = 'sf-dump-'.mt_rand();
  |  
  | Exception trace:
  |  
  | 1 Symfony\Component\VarDumper\Dumper\HtmlDumper::dump([])
  | C:\path\to\project\vendor\symfony\var-dumper\Command\Descriptor\HtmlDescriptor.php:47
  |  
  | 2 Symfony\Component\VarDumper\Command\Descriptor\HtmlDescriptor::describe(Object(Symfony\Component\Console\Style\SymfonyStyle), Object(Symfony\Component\VarDumper\Cloner\Data), [])
  | C:\path\to\project\vendor\beyondcode\laravel-dump-server\src\DumpServerCommand.php:81
  |  
  | 3 BeyondCode\DumpServer\DumpServerCommand::BeyondCode\DumpServer\{closure}(Object(Symfony\Component\VarDumper\Cloner\Data), [])
  | C:\path\to\project\vendor\symfony\var-dumper\Server\DumpServer.php:76
  |  
  | 4 Symfony\Component\VarDumper\Server\DumpServer::listen(Object(Closure))
  | C:\path\to\project\vendor\beyondcode\laravel-dump-server\src\DumpServerCommand.php:82
  |  
  | 5 BeyondCode\DumpServer\DumpServerCommand::handle()
  | C:\path\to\project\vendor\laravel\framework\src\Illuminate\Container\BoundMethod.php:29
  |  
  | 6 call_user_func_array([])
  | C:\path\to\project\vendor\laravel\framework\src\Illuminate\Container\BoundMethod.php:29
  |  
  | 7 Illuminate\Container\BoundMethod::Illuminate\Container\{closure}()
  | C:\path\to\project\vendor\laravel\framework\src\Illuminate\Container\BoundMethod.php:87
  |  
  | 8 Illuminate\Container\BoundMethod::callBoundMethod(Object(Illuminate\Foundation\Application), Object(Closure))
  | C:\path\to\project\vendor\laravel\framework\src\Illuminate\Container\BoundMethod.php:31
  |  
  | 9 Illuminate\Container\BoundMethod::call(Object(Illuminate\Foundation\Application), [])
  | C:\path\to\project\vendor\laravel\framework\src\Illuminate\Container\Container.php:572
  |  
  | 10 Illuminate\Container\Container::call()
  | C:\path\to\project\vendor\laravel\framework\src\Illuminate\Console\Command.php:183
  |  
  | 11 Illuminate\Console\Command::execute(Object(Symfony\Component\Console\Input\ArgvInput), Object(Illuminate\Console\OutputStyle))
  | C:\path\to\project\vendor\symfony\console\Command\Command.php:255
  |  
  | 12 Symfony\Component\Console\Command\Command::run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Illuminate\Console\OutputStyle))
  | C:\path\to\project\vendor\laravel\framework\src\Illuminate\Console\Command.php:170
  |  
  | 13 Illuminate\Console\Command::run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
  | C:\path\to\project\vendor\symfony\console\Application.php:886
  |  
  | 14 Symfony\Component\Console\Application::doRunCommand(Object(BeyondCode\DumpServer\DumpServerCommand), Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
  | C:\path\to\project\vendor\symfony\console\Application.php:262
  |  
  | 15 Symfony\Component\Console\Application::doRun(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
  | C:\path\to\project\vendor\symfony\console\Application.php:145
  |  
  | 16 Symfony\Component\Console\Application::run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
  | C:\path\to\project\vendor\laravel\framework\src\Illuminate\Console\Application.php:89
  |  
  | 17 Illuminate\Console\Application::run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
  | C:\path\to\project\vendor\laravel\framework\src\Illuminate\Foundation\Console\Kernel.php:122
  |  
  | 18 Illuminate\Foundation\Console\Kernel::handle(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
  | C:\path\to\project\artisan:37

```

The problem here is that `$this->currentRequest->route()` returns `null` since the `$routeResolver` is `null` and so the `$controller` stays set to `null` and `HtmlDumper` just doesn't like it.

I've solved my issue by adding this to the `RequestContextProvider`
```php

/**
* Get the context.
*
* @return array|null
*/
public function getContext(): ?array
{
if ($this->currentRequest === null) {
return null;
}

$controller = null;

if ($route = $this->currentRequest->route()) {
$controller = $route->controller;

if (! $controller && ! is_string($route->action['uses'])) {
$controller = $route->action['uses'];
}
}

if (app()->runningUnitTests()) {
$controller = $this->guessPHPUnitTestController($this->currentRequest->server->get('argv'));
}

return [
'uri' => $this->currentRequest->getUri(),
'method' => $this->currentRequest->getMethod(),
'controller' => $controller ? $this->cloner->cloneVar(class_basename($controller)) : $controller,
'identifier' => spl_object_hash($this->currentRequest),
];
}

/**
* Try to provide as much information to the dump as possible
*
* @param array $args
*
* @return string
*/
private function guessPHPUnitTestController(array $args)
{
$controller = TestCase::class;

var_export($args);

if (false === in_array('--filter', $args)) {
return $controller;
}

if (preg_match('/^[A-Z][a-zA-Z]+Test$/', $args[2])) {
return $args[2];
}

if (preg_match('/^test[A-Z][0-9a-zA-Z]+/', $args[2])) {
return $controller . '::' . $args[2];
}

return $controller;
}
```
which produces

If this way is okay for you, I can create PR with this solution :)