FIX: issue #1936 grpc cutout multithread with preserve model pin

[svandenb-dev]

This PR is fixing #1936 found by a user who identified a configuration which was not tested and was passing our CICD. The issue was concerning cutout multithread with grpc. When having Spice or Sparameter model assigned and the flag preserve_components_with_model=True, using combination og ConvexHull extent computation was throwing an error because method pins_to_preserve was mixing list of int (Id) and PadstackInstance objects. To was failling on accessing position attribute when returned object was an integer.

This PR:

• Provides returned objects consistency with always PadstackInstance objects list instead of mix Integer.
• Adjust _create_conformal extent to handle PadstackInstance object and not Integer anymore
• Add a test in CICD to make sure this configuration is catched and this bug is never introduced again.

This PR is also addressing issue #1937 with missing layer name argument in create rectangle method. Another test was added to cover this logic as it was also missing in CICD.

closes #1936
closes #1937

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 71.00%. Comparing base (5cbae21) to head (9f6b909).
⚠️ Report is 43 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1942      +/-   ##
==========================================
+ Coverage   70.20%   71.00%   +0.79%     
==========================================
  Files         261      262       +1     
  Lines       42416    42799     +383     
==========================================
+ Hits        29779    30388     +609     
+ Misses      12637    12411     -226     

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