Add 2 fields for deeplinks to exclusion grounds and selection criteria

TED Implementation (v.1.12) contradicts guide on https://code.europa.eu/eproc/eforms/docs/-/blob/main/guides/gde_003_esc.md w.r.t. to the use of BT-750.

The guide states:

Procurement Document: If the buyer selects this, it means that the supplier will find the Exclusion Grounds and/or Selection Criteria in the procurement documents. No more information needs to be provided in the notice. However, it is possible in the fields Exclusion Ground Description BT-67(b) and/or Selection Criteria Description BT-750 to provide in the text field the information to the supplier where they can find the information in the procurement documents.

Germany used this statement as basis for own national tailoring in order to implement German regulations (see https://projekte.kosit.org/eforms/eforms-de-specification/-/issues/45). There we introduced the German rule BR-DE-30

"Wenn bei BT-821 „Procurement Document“ ausgewählt wird, muss in BT-750 ein Deeplink zu der Datei mit den Eignungskriterien oder (besser noch) der Stelle in der Datei, an der sich die Eignungskriterien befinden, angegeben werden."

Rough translation into English:

If 'Procurement Document' is selected for BT-821, a description including a Deeplink must be specified in BT-750.

This had to be done even before TED implemented this, because of the challenging timelines of keeping compatibility German regulations and TEDs way of implementing the EU Regulations.

We are posting it here, because the guide needs improvements:

• to make the highlighted statement (above) an explicit business rule.
• additionally, the guide also inlcudes a potentially contradicting statement in the "Tailoring" section:

BT-750 Selection Criterion Description If BT-809 will not be used, it might also be better not to provide this field.

• However if the tailoring statement is contradictionary to the general guide statement (above) is currently a matter of interpretation. Therefore, we also suggest to use a defined list of terms on levels of requirements such as SHALL, MAY etc. e.g. according to https://www.ietf.org/rfc/rfc2119.txt in all guides.

The urgency of solving this issue is given by the fact that the current combination of TED rules makes it impossible to use BT-750 as the guide suggests:

* BR-BT-00750-0054, BR-BT-00750-0055 … BR-BT-00750-0071, BR-BT-00750-0072,

* BR-BT-00809-0012, BR-BT-00809-0013 ... BR-BT-00809-0030, BR-BT-00809-0031

in version > 1.12 .