Add multisig holder script

[Arsh-Sandhu]

• Add script to test issuing credential to a multisig AID, based on the multisig-holder.py script in Signifypy

[Arsh-Sandhu]

Created this as Draft PR as it is blocked Issue #190

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (f9b71bb) 81.42% compared to head (a3665f5) 81.42%.
Report is 7 commits behind head on development.

Additional details and impacted files

@@             Coverage Diff              @@
##           development     #191   +/-   ##
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  Coverage        81.42%   81.42%           
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  Files               46       46           
  Lines             4141     4141           
  Branches          1030     1030           
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  Hits              3372     3372           
  Misses             737      737           
  Partials            32       32           

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[nkongsuwan]

I think this PR demonstrates a similar set of issues to PR #184. Once all the issues have been resolved, I suggest these two PRs should be combined somehow.

[pfeairheller]

I'm merging in this change in because I copied the file locally and it worked with the new changes