feat: Make AppKernel with KernelTestCase compatible

[chapterjason]

• Fix AppKernel constructor to be compatible with the KernelTestCase
• Add tests for usage with KernelTestCase
• Remove BaseBundleTestCase
• Update example in Readme

fixes: #39

[chapterjason]

@Nyholm I don't know how to deal with the failing tests:

PHP Fatal error:  Declaration of Symfony\Bundle\FrameworkBundle\Test\KernelTestCase::tearDown() must be compatible with PHPUnit\Framework\TestCase::tearDown(): void in /home/runner/work/symfony-bundle-test/symfony-bundle-test/vendor/symfony/framework-bundle/Test/KernelTestCase.php on line 24

Just found the following: symfony/symfony#30071

[chapterjason]

@Nyholm I found a solution, hope we can use it like that.

[Nyholm]

Awesome. Thank you.

Could you update this PR after bumping composer.json. See #45 (comment)

[chapterjason]

@Nyholm Yes, I have done some other changes too, I would like do this at the end because of the renamed tests. :)

[chapterjason]

@Nyholm Also ready now, without the breaking change layer. Ready for a major.

[Nyholm]

Thank you for working on this

[Nyholm]

This is a new feature you snuck in. Why is it better to have an array of values rather than calling the underlying methods?

[chapterjason]

😄 Yeah.

I liked the idea of the options in the KernelTestCase, you are right, the methods are better.

The reason why I introduced this is: You only have the possibility to change the config by override the createKernel this limits it to a configuration per file and not per test. (If you don't want to boot it yourself and just want to use static:bootKernel.)

By just call the handleOptions in the createKernel you can actually passthrough everything before the kernel is booted and the container is compiled.

Another Idea, that just came in my mind, we could just create a option like config which must be a callable:

static::bootKernel(['config' => static function(AppKernel $kernel){
    $kernel->setRoutingFile(__DIR__.'/Fixtures/routes.yml');
}]);

Then we can benefit from the methods and save some lines, cause the KernelTestCase makes the booting process.

[Nyholm]

Thank you

[Nyholm]

This is great. Im happy to remove this class.