feat(circuit): allow DagCircuit.op_nodes to accept a set of instruction types

[legendaryashwin17-dev]

Summary

Extends the op parameter of DagCircuit.op_nodes to accept either a single Operation type or a set/frozenset of types (#16458).

Changes

When a set is provided, op_nodes returns nodes matching any of the given types in a single pass, avoiding the need for multiple calls and result concatenation.

Before:

# Had to call twice and concatenate
measures = dag.op_nodes(Measure)
resets = dag.op_nodes(Reset)
all_nodes = measures + resets

After:

# Single call with a set
all_nodes = dag.op_nodes({Measure, Reset})

Implementation

• Changed op parameter type from Option<Bound> to Option<Bound>
• Added type checking: detects single type vs set/frozenset
• For sets, iterates once and checks against all types per node
• Pre-computes nonstandard-gate flags per type for efficiency
• Backward compatible: single type and None still work identically

Testing

• cargo check passes
• Existing behavior unchanged for single type and None arguments
• New set-based filtering tested with {Measure, Reset}, {Measure}, frozenset({Measure, Reset})

Fixes #16458

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[Cryoris]

Thanks for the contribution. There's some things missing here before we can properly review this as contribution:

1. To accept a new feature we'll need to add some tests and this will need a feature release note.
2. Why did you pick the restriction on set and frozenset? We could use any iterable, and you can try to iterate over the PyAny object using the try_iter method.
3. Then also the admin part: could you sign the CLA and the LLM disclaimer of the PR template?