NIFI-15974 Fix PutSmbFile parent folder creation when path contains b…

[turcsanyip]

…ackslashes

Also get rid of using java.io.File for processing paths as strings because it is platform-dependent. Use string operations instead.

Summary

NIFI-15974

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  • JDK 21
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[pvillard31]

Thanks @turcsanyip - LGTM