Adds placeholders for two `np.testing` objects previously missed in https://github.com/numpy/numpy/pull/18842.

instead of `import numpy.testing as npt`.

- all of NumPy's own tests themselves use the from-import variant
- There's `import numpy.typing as npt` around in some places so
  we should not abbreviate another module import with `npt`.

Optional further enhancement: If this is a convention we also want
users to adopt, this should be mentioned in the module docstring of
`numpy.testing`.

MAINT: OrderedDict is no longer necessary from Python 3.7

ENH: Use new argument parsing for array creation functions

The array creation functions have the most to gain:

1. np.asarray is 4 times faster and commonly used.
2. Other functions are wrapped using __array_function__ in Python
   making it more difficult

This commit (unfortunatly) has to do a few things:

* Modify __array_function__ C-side dispatching to accomodate
  the fastcall argument convention.
* Move asarray, etc. to C after removing all "fast paths" from
  np.array (simplifying the code)
* Fixup imports, since asarray was imported directly in a few places
* Replace some places where `np.array` was probably used for speed
  instead of np.asarray or similar. (or by accident in 1 or 2 places)

Disallowing timedelta64+float promotion (to timedelta64) in all cases
(previously it was assymetric and "half allowed") meant that isclose,
allclose, np.ma.allclose, and assert_arrays_almost_equal (which uses
isclose), would stop work for timedelta64. Hardcoding that timedelta64
is passed on unmodified retains the old behaviour.

It may make sense to deprecate or change this behaviour in the future,
but for the 1.20 release, the behaviour should be as much unmodified
as possible.

Closes gh-18286