descriptors w/o fingerprints show "@ unknown"

[jdlcdl]

What is this PR for?

This PR will show "@ unknown" when loading a descriptor w/o origin/master fingerprint information, instead of showing the hd-key's own fingerprint.

Background:

All bip32 extended keys have their own fingerprint, and most have a parent fingerprint. These fingerprints are contained within or can be derived from the base58 xprv/xpub. But both of these are NOT what users think of "fingerprint" except for the root level bip32 master key... which is not available via xprv/xpub except for the master's depth=1 children. For this reason, the "origin info", containing "[fingerprint/derivation/path]" is included in many descriptors.

But since not all descriptors include the optional origin information, namely BlueWallet single-sig wallet backups, it is incorrect (or at least confusing to the user) to show a key's own fingerprint when they're actually expecting to see the origin/master fingerprint instead. If there is no origin information, it is better for the user to see "@ unknown" instead of a fingerprint they don't recognize.

Thank you Tadeubas for pounding this concept into my head, and for being tolerant enough till I understood. Because of this, I'm going to do better by using the terms "bip32 master fingerprint" or "origin fingerprint" instead of the more vague term "fingerprint" in future discussions/explanations.

What is the purpose of this pull request?

• [*] Bug fix
• New feature
• Docs update
• Other

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.31%. Comparing base (aaaa067) to head (12401c7).
Report is 15 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #493      +/-   ##
===========================================
- Coverage    94.85%   94.31%   -0.55%     
===========================================
  Files           74       74              
  Lines         7948     8086     +138     
===========================================
+ Hits          7539     7626      +87     
- Misses         409      460      +51     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[odudex]

Thank you @jdlcdl and @tadeubas !