Improve os_sorted performance by avoiding Path roundtrips

[Dobatymo]

Describe the feature or enhancement
When using os_sorted on a list of Path objects they are converted to string and then back to Path.

Provide a concrete example of how the feature or enhancement will improve natsort
Avoiding this roundtrip should improve performance.

Would you be willing to submit a Pull Request for this feature?
I am not really familiar with the library yet. It looks like the conversion here

natsort/natsort/natsort.py

Line 672 in 5c52a88

return utils.path_splitter(str(v))

could be moved to the else branch here

natsort/natsort/utils.py

Line 898 in 5c52a88

if not isinstance(s, PurePath):

instead

[SethMMorton]

The conversion to str(v) is because any type is technically allowed as input, but it must be a string or path object to be processed. Agreed that if the input is already Path this is extra work.

Just curious though - are you seeing a performance issue? And if so, are you sure this is the root cause of the issue?