Add x_netkan_check_parent_downloads

[Clayell]

When x_netkan_check_parent_downloads is false, do not check the github parent repos for the download count. Defaults to true. (the current behavior)
Unsure of how to test this to make sure it works.

[Clayell]

@HebaruSan Can you run the github checks again? I don't have the ability to run them on my end, and I'd like to make sure this works (and so that I can begin using it if it gets merged)

[HebaruSan]

This needs to be able to handle mods that don't have netkans, or for which the netkans are renamed to .frozen. (Note that some of the .frozen files are not valid netkans, e.g. https://github.com/KSP-CKAN/NetKAN/blob/master/NetKAN/BananaForScale.frozen.)
I think it would crash at this point.

[HebaruSan]

Confirmed; here's what those errors look like:

Traceback (most recent call last):
  File "/home/netkan/.local/bin/netkan", line 6, in <module>
    sys.exit(netkan())
             ^^^^^^^^
  File "/home/netkan/.local/lib/python3.12/site-packages/click/core.py", line 1485, in __call__
    return self.main(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/netkan/.local/lib/python3.12/site-packages/click/core.py", line 1406, in main
    rv = self.invoke(ctx)
         ^^^^^^^^^^^^^^^^
  File "/home/netkan/.local/lib/python3.12/site-packages/click/core.py", line 1873, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/netkan/.local/lib/python3.12/site-packages/click/core.py", line 1269, in invoke
    return ctx.invoke(self.callback, **ctx.params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/netkan/.local/lib/python3.12/site-packages/click/core.py", line 824, in invoke
    return callback(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/netkan/.local/lib/python3.12/site-packages/click/decorators.py", line 93, in new_func
    return ctx.invoke(f, obj, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/netkan/.local/lib/python3.12/site-packages/click/core.py", line 824, in invoke
    return callback(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/netkan/.local/lib/python3.12/site-packages/netkan/cli/utilities.py", line 64, in download_counter
    common.token).update_counts()
                  ^^^^^^^^^^^^^^^
  File "/home/netkan/.local/lib/python3.12/site-packages/netkan/download_counter.py", line 402, in update_counts
    self.get_counts()
  File "/home/netkan/.local/lib/python3.12/site-packages/netkan/download_counter.py", line 310, in get_counts
    nk = Netkan(self.nk_repo.nk_path(ckan.identifier), game_id=self.game_id)
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/netkan/.local/lib/python3.12/site-packages/netkan/metadata.py", line 33, in __init__
    self.contents = self.filename.read_text(encoding='UTF-8')
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/pathlib.py", line 1029, in read_text
    with self.open(mode='r', encoding=encoding, errors=errors) as f:
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/pathlib.py", line 1015, in open
    return io.open(self, mode, buffering, encoding, errors, newline)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
FileNotFoundError: [Errno 2] No such file or directory: '/tmp/ksp/NetKAN/NetKAN/sidosUraniaSystem.netkan'

[Clayell]

I pushed a commit that checks if the netkan file exists first, which is also done by auto_freezer.py in a very similar way. Should account for both situations?