feat: script to get multisig xpub from seed easily

[luislhl]

Acceptance Criteria

• We should be able to run make multisig_xpub_from_seed seed="<seed words>" to get a multisig xpub from seed

Motivation

• Some people were mistakenly using make xpub_from_seed for this.
• It will make it easier to generate a multisig xpub in automated environments

Security Checklist

• Make sure you do not include new dependencies in the project unless strictly necessary and do not include dev-dependencies as production ones. More dependencies increase the possibility of one of them being hijacked and affecting us.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.19%. Comparing base (1d1c899) to head (cf410e2).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #520   +/-   ##
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  Coverage   90.19%   90.19%           
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  Files          54       54           
  Lines        2325     2325           
  Branches      439      439           
=======================================
  Hits         2097     2097           
  Misses        211      211           
  Partials       17       17           

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