[11.x] Inspect exception of assertThrows

[gdebrauwer]

The assertThrows test method makes it possible to assert if a specific exception is thrown. You can also assert the message of the exception. But what if you want to assert other data/properties of the thrown exception? That is currently not possible, but this PR fixes that.

$this->assertThrows(
    fn () => throw new FooException(),
    fn (FooException $exception) => $exception->getBar() === 'baz'
);