`aesara.as_symbolic` is a new function that converts all eligible objects to
`Variable`s.  Unlike `aesara.tensor.as_tensor_variable`, `as_symbolic` will
convert `None`s and `slice`s, or any other types that have equivalent Aesara `Type`s.

Fixes https://github.com/aesara-devs/aesara/issues/733
Clean up tests and config variable cache_optimizations

Not creating a temporary list will enable early exit of all and any.
Faster to create tuple than list contaning constants.
Removed duplicated definition of method.

versioneer must be rerun to support Python 3.11. At the same time, the support
for Python 3.6 was further reduced and also some odd Python 2.7-leftovers removed.

Closes #703.

(I've searched and these are the ones I found.)

In addition, the value is printed (and sometimes the data type).

There was a direct access to a NumPy configuration which was
removed in 1.22. This PR removes the special handling and rely
on accessing the configuration in a controlled way to avoid later
issues.

These changes remove the stride-based manual computation of the new shape, since
those are potentially sensitive to broadcasted arrays with no strides.

`Solve` has also been changed to match SciPy.

* Fix class, attribute, and function formatting
* Update the relevant glossary terms and references to them
* Rename documentation to better reflect their content
* Remove redundant documentation
* Reorder index so that it starts with the basic, necessary articles
* Grammar and wording updates