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fix(mypyc): keep `Function` weak-referenceable on the compiled wheels (#319)

* fix(mypyc): keep `Function` weak-referenceable on the compiled wheels

Closes #317
Closes #318

Since 2.10.0 ships `mypyc`-compiled wheels with `_function.py` in the compile
set, `Function` is a native class. A native class has neither `__weakref__` nor
`__dict__`, and both absences are load-bearing for downstream code.

`jax.jit` registers the callable it wraps in a weakly-keyed cache, so every
`jax.jit(<dispatched function>)` now raises on first call:

    TypeError: cannot create weak reference to 'Function' object

That is issue #318. The missing instance dictionary is issue #317: the
`_DocDescriptor` attached to `Function` defines only `__get__`, so `f.__doc__ =
...` has nowhere to land and raises `AttributeError: ... is read-only`.

`__weakref__` cannot simply be declared. `mypyc` emits the member only when the
class already carries an instance dictionary, and on CPython 3.12+ the
managed-dict path drops it even then. Two nearby escape hatches do not work:
`@mypyc_attr(native_class=False)` on `Function` fails codegen outright with
`KeyError: 'object'` (and would forfeit the native-class win on the hottest
class in the library), and a `native_class=False` base declared in the *same*
compiled module still yields no `__weakref__` -- compiled and checked.

Inheriting from a base in a module that is *not* in the compile set does work:
`mypyc` then builds the class through CPython's normal type machinery, which
grants `__dict__` and `__weakref__`, and the class stays native. Hence `NativeBase`,
which lives in the interpreted `_mypyc` module beside the other `mypyc`
accommodations, and a comment on the `include` list so that module is not swept in
later.

* refactor(mypyc): retire the `native_class=False` invoke wrappers

`_InvokedMethod` and `_BoundInvokedMethod` opted out of native compilation for
exactly one reason, stated in `_InvokedMethod`'s own docstring: `functools.... (continued)

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