Add in new stream poster when sending GRANT and credential

[pfeairheller]

This PR includes adding the new StreamPoster to GRANT message and credential streaming.

[codecov]

Codecov Report

Attention: 8 lines in your changes are missing coverage. Please review.

Comparison is base (56c20c7) 91.66% compared to head (d6d62f3) 91.36%.

Files	Patch %	Lines
src/keria/app/agenting.py	68.42%	6 Missing ⚠️
src/keria/app/indirecting.py	85.71%	2 Missing ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##           development     #130      +/-   ##
===============================================
- Coverage        91.66%   91.36%   -0.31%     
===============================================
  Files               37       35       -2     
  Lines             5987     5824     -163     
===============================================
- Hits              5488     5321     -167     
- Misses             499      503       +4     

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