Add support to QuantumCircuit and DAGCircuit methods involving Expr expressions

[jakelishman]

What should we add?

This forms a lot of the work needed for actual use of the initial classical-expression design document.

Depends on #10223 and #10224.

Contained issues

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1. Add support for mapping Expr values in DAG/QC converters qiskit-terra#10226
   type: feature request +1
   
2. Add support for Expr values to QuantumCircuit.compose qiskit-terra#10227
   type: feature request +1
   
3. Add support for Expr values to DAGCircuit.compose qiskit-terra#10230
   type: feature request +1
   
4. Add support for Expr values to DAGCircuit.replace_block_with_op qiskit-terra#10231
   type: feature request +1
   
5. Add support for Expr values to DAGCircuit.__eq__ qiskit-terra#10359
   +0
   
6. Add support for Expr to DAGCircuit.substitute_node_with_dag qiskit-terra#10379
   type: feature request +1
   
7. Add support for Expr to DAGCircuit.substitute_node qiskit-terra#10380
   type: feature request +1
   

In addition to the DAGCircuit methods that are explicitly called out above, I substitute_node_with_block and substitute_node both technically need updating with support for Expr values. However, I think in practice that these operations do not make sense in the same way with control flow, and since we need to rework how the DAGCircuit data structure works with control flow anyway, I don't think they will actually need touching.

edit: in having done this, I think it's actually simple enough and meaningful to define the behaviour for substitute_node_with_dag and substitute_node, and likely will be useful for PRs in the vein of #9580.

[jakelishman]

As of right now, the PRs:

• Add Expr supprt to DAGCircuit simple constructors #10362
• Add Expr support to QuantumCircuit.compose #10375
• Add Expr support to DAGCircuit.compose #10377
• Add Expr support to DAGCircuit.replace_block_with_node #10383
• Add support for semantic equality checking of Exprs in DAGCircuit #10367
• Add Expr support to DAGCircuit.substitute_node_with_dag #10381
• Add Expr support in DAGCircuit.substitute_node #10382

close every issue in this task list. Once the task list is complete, this issue can be closed as completed.

[jakelishman]

All contained issues now closed.