Openpulse AST definitions shadow OpenQASM AST definitions with incompatible types

[braised-babbage]

The following program fails to typecheck with mypy 1.27:

from openpulse.ast import CalibrationDefinition, CalibrationStatement

def foo(stmt: CalibrationDefinition):
    stmt.body = []

The mypy error is

mypy example.py
example.py:4: error: Incompatible types in assignment (expression has type "list[Never]", variable has type "str")  [assignment]
Found 1 error in 1 file (checked 1 source file)

The variable has type "str" comes from the openqasm3.ast.CalibrationDefinition, which does use str for the body field.