Fix len parameter handling: Unit tests for gRPC ,interpretor and session

[rahur-NI]

• This contribution adheres to CONTRIBUTING.md.
• I've updated CHANGELOG.md if applicable.
• I've added tests applicable for this pull request

What does this Pull Request accomplish?

This PR continues the work from Fixing size parameter handling.
It includes the following changes:

• Added a new niFake API, MixedIviDanceAndLenMechanism, to validate mixed size mechanisms:
  • len-sized input array
  • Output array with IVI-dance mechanism
• Updated nifake.proto to include new methods ('MixedIviDanceAndLenMechanism' and 'MultipleArraysDifferentSize').

List issues fixed by this Pull Request below, if any.

None

What testing has been done?

• Tox run success.
• Added/updated unit tests:
  • MultipleArraysDifferentSize
    • gRPC
      • test_multiple_arrays_different_size: forwards both arrays with correct sizes
      • test_multiple_arrays_different_size_none_input: forwards None correctly and treats size as 0
    • Library interpreter
      • test_multiple_arrays_different_size: driver call receives both arrays with expected size arguments
      • test_multiple_arrays_different_size_none_input: one array is passed as None with size 0
    • Session
      • test_multiple_arrays_different_size_none_input: session forwards values_array and None unchanged to interpreter
  • MixedIviDanceAndLenMechanism
    • gRPC
      • test_mixed_ivi_dance_and_len_mechanism: verifies request mapping for a mixed-mechanism API (len-sized input array in grpc request for a method that also uses IVI-dance output behavior).
    • Library interpreter
      • test_mixed_ivi_dance_and_len_mechanism: verifies IVI-dance two-call pattern

[codecov-commenter]

Codecov Report

❌ Patch coverage is 71.42857% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.12%. Comparing base (cf288d4) to head (95713b9).

Files with missing lines	Patch %	Lines
generated/nifake/nifake/session.py	50.00%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2165   +/-   ##
=======================================
  Coverage   90.12%   90.12%           
=======================================
  Files          71       71           
  Lines       18675    18682    +7     
=======================================
+ Hits        16830    16838    +8     
+ Misses       1845     1844    -1     

Flag	Coverage Δ
codegenunittests	84.87% <ø> (ø)
nidcpowersystemtests	94.65% <ø> (+0.04%)	⬆️
nidcpowerunittests	89.53% <ø> (ø)
nidigitalsystemtests	92.26% <ø> (ø)
nidigitalunittests	68.44% <ø> (ø)
nidmmsystemtests	92.72% <ø> (ø)
nifakeunittests	85.68% <71.42%> (+0.07%)	⬆️
nifgensystemtests	94.61% <ø> (ø)
nimodinstsystemtests	73.85% <ø> (ø)
nimodinstunittests	94.20% <ø> (ø)
nirfsgsystemtests	82.40% <ø> (ø)
niscopesystemtests	92.94% <ø> (ø)
niscopeunittests	43.20% <ø> (ø)
nisesystemtests	91.50% <ø> (ø)
niswitchsystemtests	82.03% <ø> (ø)
nitclksystemtests	94.87% <ø> (ø)
nitclkunittests	98.26% <ø> (ø)

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Files with missing lines	Coverage Δ
generated/nifake/nifake/_grpc_stub_interpreter.py	83.39% <100.00%> (+0.59%)	⬆️
generated/nifake/nifake/session.py	77.60% <50.00%> (-0.03%)	⬇️

... and 1 file with indirect coverage changes

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