RichConsole: Prettify m1 CLI console using rich #4806

[gziz]

Why are these changes needed?

As requested in #4806

• Use the rich library to prettify the console.
  • Using Panel to wrap the messages
  • Different colors for each agent in M1.
• As suggested by @gagb, placing user to the left, Orchestrator in the middle and any other agent to the left.

Some screenshots:

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

Attention: Patch coverage is 0% with 88 lines in your changes missing coverage. Please review.

Project coverage is 69.84%. Comparing base (44b9bff) to head (d03c8e9).

Files with missing lines	Patch %	Lines
...es/autogen-ext/src/autogen_ext/ui/_rich_console.py	0.00%	86 Missing ⚠️
...ackages/autogen-ext/src/autogen_ext/ui/__init__.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5123      +/-   ##
==========================================
- Coverage   70.39%   69.84%   -0.56%     
==========================================
  Files         174      176       +2     
  Lines       11083    11171      +88     
==========================================
  Hits         7802     7802              
- Misses       3281     3369      +88     

Flag	Coverage Δ
unittests	69.84% <0.00%> (-0.56%)	⬇️

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[gagb]

@gziz and @ekzhu the only remaining issue is lack of code coverage. Should we do that now or later?