🚚 Move IQM conversion support to QDMI-on-IQM

[burgholzer]

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Goal

Move the provider-specific IQM JSON converter and related IQM operation handling from generic MQT Core code to QDMI-on-IQM.

Scope

• Move qiskit_to_iqm_json and its tests to QDMI-on-IQM.
• Move or register provider-specific MoveGate conversion behavior without making the generic Qiskit adapter depend on IQM.
• Introduce the smallest codec/program-format registration seam needed for a provider to advertise and implement IQM JSON.
• Reconcile this ownership change with the behavior currently discussed in ✨ Support IQM JSON, QIR, and QPY in the QDMI Qiskit backend #1348.
• Do not decide the ownership of the generic Qiskit adapter in this issue.

Acceptance criteria

• Core contains no IQM-specific JSON conversion logic.
• QDMI-on-IQM owns and tests IQM program conversion.
• Generic QDMI and Qiskit code selects provider codecs without hard-coded IQM branches.
• Existing IQM execution behavior remains covered by cross-repository tests.