Remove deepcopy usage in dag_to_circuit (#1431)
Remove deepcopy usage in dag_to_circuit (#1431)

* Remove deepcopy usage in dag_to_circuit

This commit attempts to improve the performance of dag_to_circuit by
removing the deepcopy usage. Instead this switches to  creating a
circuit object using the normal constructors while iterating over the
dag.

* Fix u_base name

* Fix CX is not cx

* Remove random_name

* CX is cx_base not cx

* Fix bit args mismatch when using coupling map

* Remove unused imports

* Fix handling of simulator instructions

QISKit/qiskit-sdk-py,QISKit/qiskit-sdk-py,QISKit/qiskit-sdk-py