Register the German addons in the bundle

[pedrorfdez]

Adds gobl.de.xinvoice's XRechnung and ZUGFeRD addons to the bundle, so every service that imports it (silo today) can validate documents declaring de-xrechnung-v3 and de-zugferd-v2 once GOBL core stops shipping them. Imported as two packages rather than one addon package; consolidating can come later.

Before merge: swap the gobl.de.xinvoice pseudo-version for the released tag.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 72.58%. Comparing base (026ec83) to head (553335d).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #40   +/-   ##
=======================================
  Coverage   72.58%   72.58%           
=======================================
  Files          47       47           
  Lines        1988     1988           
=======================================
  Hits         1443     1443           
  Misses        465      465           
  Partials       80       80           

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