Update AGS to Use AgentChat Declarative Config Serialization

[victordibia]

Why are these changes needed?

This PR updates AGS to use the declarative config serialization native to AgentChat.
The effect? You can build your teams/artifacts directly in python, run team.dump_component() and immediately run it in AGS.

Some change details:

• Removes ComponentFactory. Instead TeamManager just loads team specs directly using Team.load_component.
• Some fixes to the UI to simplify drag and drop experience.
• Improve layout of nodes...

Related issue number

Closes #4439
Closes #5172

Checks

• 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.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.

cc @EItanya @nour-bouzid

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 70.59%. Comparing base (fca1de9) to head (f55d3db).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5261   +/-   ##
=======================================
  Coverage   70.59%   70.59%           
=======================================
  Files         180      180           
  Lines       11668    11668           
=======================================
  Hits         8237     8237           
  Misses       3431     3431           

Flag	Coverage Δ
unittests	70.59% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.