remove testing folder

[arnoweiss]

This is not relevant for the first release candidate.

Discussed in #125

^{Originally posted by arnoweiss December 11, 2024}
We currently still have a folder that contains test-files for VCs and VPs. My feeling is that these fixtures should rather be part of the Technology Conformity Kit. The content is outdated (still contains IATP and the tests themselves are on the brink of the protocol's scope.

This should be either updated or removed from this repository before an upcoming release. Parking it in the (currently empty) tck might be an intermediary solution.

[arnoweiss]

cc @mspiekermann