bpo-32176: Set CO_NOFREE in the code object constructor (GH-4675)

bpo-32176: Set CO_NOFREE in the code object constructor (GH-4675)

Previously, CO_NOFREE was set in the compiler, which meant
it could end up being set incorrectly when code objects
were created directly. Setting it in the constructor based
on freevars and cellvars ensures it is always accurate,
regardless of how the code object is defined.