Fix alias bug

[TheGupta2012]

Summary of changes

• Aliased bits can be used in combination with global qubits. Eg -

    OPENQASM 3;
    include "stdgates.inc";
    qubit[4] q;
    bit[4] c;

    let alias = q[0:2];

    h q;
    measure q -> c;

    if(c[1] == 1){
        cx alias[1], q[2];
    }

• The semantic check currently raises the error -

pyqasm.exceptions.ValidationError: Missing register declaration for q in operation QuantumGate ...

• Reason is that while getting the bits of cx alias[1], q[2]; we force alias replacement for all bits. This is an incorrect assumption as q[2] is a not an aliased bit.