Update to primitives v2

[airwoodix]

Primitives V1 (especially BackendEstimator and BackendSampler) are deprecated since Qiskit 1.2 (see e.g. Qiskit/qiskit#12497 (comment)). We therefore need to migrate to using the primitives V2.

Since primitives v2 were only introduced in 1.0, this will likely imply dropping support for older Qiskit versions.

Cc @fg-aqt @jbrixon @wilfried-huss @chma100

[airwoodix]

Neither qiskit-algorithms (qiskit-community/qiskit-algorithms#136) nor qiskit-optimization (qiskit-community/qiskit-optimization#587) support primitives v2. Do we know if other major support packages actually support them?