REFACTOR-#6805: Move all IO functions to 'modin.pandas.io' module

[dchigarev]

What do these changes do?

This PR moves the following IO function to the modin.pandas.io module:

• from_pandas()
• from_arrow()
• from_dataframe()
• from_non_pandas()
• to_pandas()
• to_numpy()

The try_cast_to_pandas() function was not moved as IMO it's more of a utility function rather than a pure IO. However, if reviewers think differently, I still can move it to the IO module.

• first commit message and PR title follow format outlined here

  NOTE: If you edit the PR title to match this format, you need to add another commit (even if it's empty) or amend your last commit for the CI job that checks the PR title to pick up the new PR title.

• passes flake8 modin/ asv_bench/benchmarks scripts/doc_checker.py
• passes black --check modin/ asv_bench/benchmarks scripts/doc_checker.py
• signed commit with git commit -s
• Resolves Move all IO functions to the modin.pandas.io module #6805
• tests are passing
• module layout described at docs/development/architecture.rst is up-to-date

[YarShev]

Should we use @functools.wraps(func) here or assign some attributes like name, doc to deprecated_func from a deprecated function to be called?

[dchigarev]

We can't do this. The code building a decorator is being executed at the time of the module's initialization, which means, that we cannot do circular imports at this point. See the simplified example:

def create_deprecated(msg):
    # the code in this function is being executed at the time of module initialization,
    # meaning that the following line will trigger the circular import error:
    # from modin.pandas.io import to_pandas

    # can't use this as we haven't imported 'to_pandas' yet
    # @functols.wrap(to_pandas)
    def wrapper(*args, **kwargs):
        # we can only import actual 'to_pandas' here as this code is being executed
        # when the function is called and all the modules are initialized
        from modin.pandas.io import to_pandas
        return to_pandas(*args, **kwargs)

    return wrapper
   
to_pandas = create_deprecated("to_pandas")

[YarShev]

Left a few comments. Other than that, LGTM.

[anmyachev]

Let's not use them together: https://stackoverflow.com/questions/128573/using-property-on-classmethods/64738850#64738850

[dchigarev]

changed to using this as a classmethod-constructor

it didn't work, will find another solution

UPD: ended up writing a custom-written decorator allowing class properties

[anmyachev]

LGTM!