feat(ZUGFERD): Add dedicated ZUGFERD v1/v2 support and refine invoice format detection logic

readme.hints.md

@@ -0,0 +1,12 @@
+For testing use
+
+```typescript
+import {tap, expect} @push.rocks/tapbundle
+```
+
+tapbundle exports expect from @push.rocks/smartexpect
+You can find the readme here: https://code.foss.global/push.rocks/smartexpect/src/branch/master/readme.md
+
+Don't use shortcuts when doing things, e.g. creating sample data in order to not implement something correctly, or skipping tests, and calling it a day.
+
+It is ok to ask questions, if you are unsure about something.