fix: upsert contact didn't work with accessKeys

[chris-4chain]

Unlike as we do for the other contact endpoints, the upsert endpoint function relied on xpub instead of xpub_hash.
Because the -web-backend uses accessKeys for requests authorization, the upsert didn't work.

More context here:
https://github.com/bitcoin-sv/spv-wallet/blob/fix-upsert-contact/server/auth/middleware.go#L81-L120

Pull Request Checklist

• 📖 I created my PR using provided : CODE_STANDARDS
• 📖 I have read the short Code of Conduct: CODE_OF_CONDUCT
• 🏠 I tested my changes locally.
• ✅ I have provided tests for my changes.
• 📝 I have used conventional commits.
• 📗 I have updated any related documentation.
• 💾 PR was issued based on the Github or Jira issue.

[github-actions]

Manual Tests

💚 Manual testing by @arkadiuszos4chain resulted in success.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 60.00000% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 53.17%. Comparing base (cffc32a) to head (5c2375d).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #556      +/-   ##
==========================================
- Coverage   53.17%   53.17%   -0.01%     
==========================================
  Files         194      194              
  Lines       10896    10895       -1     
==========================================
- Hits         5794     5793       -1     
  Misses       4553     4553              
  Partials      549      549              

Flag	Coverage Δ
unittests	53.17% <60.00%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
engine/action_contact.go	63.33% <100.00%> (-0.25%)	⬇️
actions/contacts/upsert.go	0.00% <0.00%> (ø)

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