chore: Add context to errors thrown on cbor decode

[frederikrothenberger]

We have the issue in Internet Identity that people complain about hard to diagnose issues. In particular, we regularly encounter users faced with the "failed to parse" message thrown out of borc. It would be very helpful to know what the input was that caused that error.

How Has This Been Tested?

Against existing test suite.

Checklist:

• [x] My changes follow the guidelines in CONTRIBUTING.md.
• [x] The title of this PR complies with Conventional Commits.
• [x] I have edited the CHANGELOG accordingly.
• [x] I have made corresponding changes to the documentation.