Fix local file

[atomdmac]

Addresses the following issues:

• The validate function did not allow a value of local_file for the save config option.
• The ImageGrab.save() and makedirs() functions seemed not to work when using relative paths.

[codesandbox[bot]]

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[trducng]

@TobinPalmer Can you work on this PR. I have similar workaround and it would be great to have it resolved upstream.