fix: drop agent EID suffix on multisig OOBI by default

[kentbull]

This has been a constant source of confusion for years and should return the intuitive result by default, the multisig Agent OOBI with no agent EID suffix.

The includeEid URL parameter allows using the old behavior, if desired.

SignifyTS PR: WebOfTrust/signify-ts#400
SignifyPy PR: WebOfTrust/signifypy#150

[codecov]

Codecov Report

❌ Patch coverage is 98.55072% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 87.86%. Comparing base (8a1b9e2) to head (73fbcab).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/keria/app/aiding.py	95.65%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #447      +/-   ##
==========================================
+ Coverage   87.75%   87.86%   +0.10%     
==========================================
  Files          26       26              
  Lines        5825     5877      +52     
==========================================
+ Hits         5112     5164      +52     
  Misses        713      713              

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