slcli image list should use an iterative call

[allmightyspiff]

https://github.com/softlayer/softlayer-python/blob/master/SoftLayer/managers/image.py#L73

The image list API calls should use self.client.iter_call to page through results. Also set the limit to maybe 50, the command takes a LONG time to execute as it is.

Also there is this error:

$> slcli image list
An unexpected error has occured:
Traceback (most recent call last):
  File "C:\Users\allmi\Code\py311\Lib\site-packages\SoftLayer\CLI\core.py", line 183, in main
    cli.main(**kwargs)
  File "C:\Users\allmi\Code\py311\Lib\site-packages\click\core.py", line 1055, in main
    rv = self.invoke(ctx)
         ^^^^^^^^^^^^^^^^
  File "C:\Users\allmi\Code\py311\Lib\site-packages\click\core.py", line 1657, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\allmi\Code\py311\Lib\site-packages\click\core.py", line 1657, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\allmi\Code\py311\Lib\site-packages\click\core.py", line 1404, in invoke
    return ctx.invoke(self.callback, **ctx.params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\allmi\Code\py311\Lib\site-packages\click\core.py", line 760, in invoke
    return __callback(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\allmi\Code\py311\Lib\site-packages\click\decorators.py", line 84, in new_func
    return ctx.invoke(f, obj, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\allmi\Code\py311\Lib\site-packages\click\core.py", line 760, in invoke
    return __callback(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\allmi\Code\py311\Lib\site-packages\SoftLayer\CLI\image\list.py", line 36, in cli
    images = [image for image in images if not image['parentId']]
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\allmi\Code\py311\Lib\site-packages\SoftLayer\CLI\image\list.py", line 36, in <listcomp>
    images = [image for image in images if not image['parentId']]
                                               ~~~~~^^^^^^^^^^^^
TypeError: string indices must be integers, not 'str'

Feel free to report this error as it is likely a bug:
    https://github.com/softlayer/softlayer-python/issues
The following snippet should be able to reproduce the error

TODO

1. Image list API calls should use iter_call in smaller batches (say 10-25?)
2. Image list CLI should return a MAX of 100 images I think, but break that up over several api calls
3. Fix the error about parentId