Fix gcs client pagination

[derek-globus]

What?

• Added marker and page_size parameters to 2 iterable gcs_client routes
  • gcs_client.get_storage_gateway_list(...)
  • gcs_client.get_role_list(...)

Why?

• Pagination on those two routes is broken
  • As described in this ticket, iterating through gcs_client.paginated.get_storage_gateway_list() raises an unexpected keyword argument 'marker'.

Testing

Manually tested in python console:

data = gcs.paginated.get_storage_gateway_list(page_size=1)
for idx, page in enumerate(data.pages()):
    print(f"Page {idx}: {len(page['data'])} item")
    
Page 0: 1 item
Page 1: 1 item

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📚 Documentation preview 📚: https://globus-sdk-python--738.org.readthedocs.build/en/738/