Pathlib support for the IO registry

[wasade]

The read and potentially the write methods of the IO registry may not be aware of how to interact with pathlib.Path:

(skdev-py310) 8:34:48 (dtmcdonald@there):scikit-bio@biom_format$ cat foo.fasta 
>a
ATGC
>b
TTGC
(skdev-py310) 8:34:53 (dtmcdonald@there):scikit-bio@biom_format$ python
Python 3.10.13 (main, Sep 11 2023, 08:39:02) [Clang 14.0.6 ] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import skbio, pathlib
>>> list(skbio.read('foo.fasta', format='fasta'))
[Sequence
---------------------
Metadata:
    'description': ''
    'id': 'a'
Stats:
    length: 4
---------------------
0 ATGC, Sequence
---------------------
Metadata:
    'description': ''
    'id': 'b'
Stats:
    length: 4
---------------------
0 TTGC]
>>> list(skbio.read(pathlib.Path('foo.fasta'), format='fasta'))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/dtmcdonald/ResearchWork/software/scikit-bio/skbio/io/registry.py", line 1180, in read
    return io_registry.read(file, format=format, into=into, verify=verify, **kwargs)
  File "/Users/dtmcdonald/ResearchWork/software/scikit-bio/skbio/io/registry.py", line 495, in read
    return (x for x in itertools.chain([next(gen)], gen))
  File "/Users/dtmcdonald/ResearchWork/software/scikit-bio/skbio/io/registry.py", line 518, in _read_gen
    with _resolve_file(file, **io_kwargs) as (file, _, _):
  File "/Users/dtmcdonald/miniconda3/envs/skdev-py310/lib/python3.10/contextlib.py", line 135, in __enter__
    return next(self.gen)
  File "/Users/dtmcdonald/ResearchWork/software/scikit-bio/skbio/io/util.py", line 222, in _resolve_file
    file, source, is_binary_file = _resolve(file, **kwargs)
  File "/Users/dtmcdonald/ResearchWork/software/scikit-bio/skbio/io/util.py", line 77, in _resolve
    raise IOSourceError("Could not open source: %r (mode: %r)" % (file, mode))
skbio.io._exception.IOSourceError: Could not open source: PosixPath('foo.fasta') (mode: 'r')
>>>