Make ID always searchable in DC_Table

[Toflar]

Problem:

1. Go to https://demo.contao.org/contao?do=form
2. Try to search for Form ID 3
3. You won't get any results.

The reason for that is that Form ID relates to the HTML ID and not the database ID. This is confusing because e.g. in tl_article or tl_page you can search for the database ID so you expect to be able to do that in forms as well.

I think the easiest fix for that problem is to allow searching for the database ID for form related stuff as well.

[Toflar]

Updated, now id is always searchable. The label definition is useless as well because ID is the default :)

[leofeyer]

Perfect 🎉

[leofeyer]

Thank you @Toflar.