feat: grpc common layer architecture, bodies stub and admin stub implementation

[RobPasMue]

Description

• Move gRPC calls to a common layer
• Include the bodies stub implementation as a reference
• Include the admin stub implementation as a reference

Issue linked

Related to #1817

[codecov]

Codecov Report

Attention: Patch coverage is 91.44928% with 59 lines in your changes missing coverage. Please review.

Project coverage is 90.29%. Comparing base (8a5567c) to head (a4ecb7c).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...ys/geometry/core/_grpc/_services/v0/conversions.py	84.86%	28 Missing ⚠️
...c/ansys/geometry/core/_grpc/_services/v0/bodies.py	94.78%	11 Missing ⚠️
src/ansys/geometry/core/_grpc/_version.py	78.43%	11 Missing ⚠️
...rc/ansys/geometry/core/_grpc/_services/_service.py	80.64%	6 Missing ⚠️
src/ansys/geometry/core/designer/body.py	92.85%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1867      +/-   ##
==========================================
+ Coverage   90.18%   90.29%   +0.11%     
==========================================
  Files          92      102      +10     
  Lines        8902     9304     +402     
==========================================
+ Hits         8028     8401     +373     
- Misses        874      903      +29     

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