Fix Python platform argument matching

[flowerthrower]

Summary

• accept each target argument's platform-arg as a Python/runtime key
• retain the existing config-key and prefixed nvq++ spellings
• restore documented Python kwargs for existing backends such as Scaleway, IonQ, and IQM

Testing

• uvx prek run --files cudaq/lib/Target/Yaml/TargetConfigYaml.cpp
• focused C++ comparison using setup-mlir 22.1.4:
  • unmodified main drops Scaleway's max_duration
  • patched code forwards Scaleway's max_duration, IonQ's qpu, and IQM's url
  • patched code retains --scaleway-max-duration
• git diff --check

Context

This also addresses the target-argument mismatch identified while reviewing #4882 and fixes #5202

[copy-pr-bot]

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