AGS Improvements (Add Test Button in Team Builder View + Others)

[victordibia]

Why are these changes needed?

• Add ability to test teams in Team Builder view
• Update Gallery (add deep research default team, fix bug with gallery serialization)
• UI fixes
  • improve drag drop component experience
  • improve new session experience (single click rather than 3 clicks to create a session)
  • fix bug with stop reason not being shown in some cases

Related issue number

Closes #5392

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.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.11%. Comparing base (73a7ba5) to head (72f7657).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5416   +/-   ##
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  Coverage   78.11%   78.11%           
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  Files         158      158           
  Lines        9590     9590           
=======================================
  Hits         7491     7491           
  Misses       2099     2099           

Flag	Coverage Δ
unittests	78.11% <ø> (ø)

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[ekzhu]

@victordibia For the deep research team, I think we can add a planner agent and use a custom selector function so after every other agent, the planner agent is selected to reason the next step. This will make the behavior similar to M1.

[victordibia]

Thats a good idea .. should we create an issue for this, and make it a separate PR?

[ekzhu]

Thats a good idea .. should we create an issue for this, and make it a separate PR?

Let's create a separate issue and pr