FEATURE: Add creationDate to SecondFactor and ordering to second factor list in backend

[JamesAlias]

This adds a creationDate field to the SecondFactor entity. It's always nice to have this information and we can order by it.

The default ordering in the backend module list is account descending and creationDate descending.

SecondFactors without a creationDate will get a default value.
The default value will be shown as '-' in the backend module list.

[Benjamin-K]

I'd prefer having

protected $defaultOrderings = [
    'account' => 'ASC',
    'creationDate' => 'DESC'
];

(at least that's what i'd expect).

But I really like having additional infos where easily possible 😍