Remove argparse from get_client function signature

[ryantwolf]

Main items:

• [x] Refactor get_client function to not use argparse
• [x] Add parse_client_args function to bridge argparse to new get_client
• [x] Update all get_client invocations
• [x] Allow get_client to be imported from root module like from nemo_curator import get_client
• [x] Update documentation
• [x] Test all scripts

Other changes:

• Modify how find_exact_duplicates.py determines whether to use CPU or GPU.
• Fix broken links in user guide.

[Maghoumi]

@ryantwolf I think we should have this functionality. I was trying to use the Curator through a notebook and had to do some gymnastics to create a client using get_client().

If this is too much work for now, maybe a simple workaround would be to have an equivalent of add_distributed_args(), but return a dictionary of the required arguments. This way the user can pass that dict instance to get_client() and still be able to use the code in a notebook environment.