Add support for switch statements in qasm3_to_qir converter

[TheGupta2012]

Feature Description

• openqasm 3 also supports switch statements which allow users to condition statement execution based on integral variables.

Implementation (Optional)

• The pyqir._native module does have a definition of the Switch construct but it is not entirely clear how that can be incorporated into the converter. A good starting point would be the pyqir._native definition and the openqasm switch reference

• It would be good to have a handler for the switch, like the _visit_branching_statement. Since switch is also a type of branching instruction, we can either expand this method or create a new handler.