[CAP] [Feature] Get list of actors from directory service.

[rajan-chari]

Why are these changes needed?

Search for Actors connected to the network by name (regex)

Actors can dynamically join a group in CAP, this feature allows participants get a list of Actors currently connected to the network.

Checks

• [x] I've included any doc changes needed for https://microsoft.github.io/autogen/. See https://microsoft.github.io/autogen/docs/Contribute#documentation to build and test documentation locally.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 36.88%. Comparing base (38b64b6) to head (588e4b7).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2073   +/-   ##
=======================================
  Coverage   36.88%   36.88%           
=======================================
  Files          68       68           
  Lines        7062     7062           
  Branches     1540     1540           
=======================================
  Hits         2605     2605           
  Misses       4228     4228           
  Partials      229      229           

Flag	Coverage Δ
unittests	36.88% <ø> (ø)

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[rajan-chari]

All set @ekzhu. Thanks for the review. I will use Draft next time.