feat: Add recursive sudirectories and files extraction.

[nepiskopos]

Pull request type

select from below

• Feature enhancement --> This one

Which ticket is resolved?

• None

What does this PR change?

• Adds the option to set a target directory and extract this directory including all of its subdirectories and the files contained in each subdirectory (including the parent).

Other information

[miurahr]

@nepiskopos Thank you for contribution!

Could you please also update manual document?
You extend API so we need to update the document docs/api.rst and docs/authors.rst

Also please check coding style because of a failure of tox check in CI test.

   py7zr/py7zr.py:564:50: E712 comparison to False should be 'if cond is False:' or 'if not cond:'
  py7zr/py7zr.py:568:52: E712 comparison to True should be 'if cond is True:' or 'if cond:'
  py7zr/py7zr.py:1006:17: BLK100 Black would make changes.
  py7zr/py7zr.py:1006:126: E501 line too long (136 > 125 characters)

You can check your side by running tox -e check

[miurahr]

pip install black
black py7zr/py7zr.py

[nepiskopos]

pip install black
black py7zr/py7zr.py

Thanks, I used black to change line formatting. Maybe the CI failure issues are fixed?