Adding CloseDynamicLibrary() to arrow/util/io_util.h

[argmarco-tkd]

Adding CloseDynamicLibrary() to arrow/util/io_util.h

This work is part of a series of PRs created to merge the "DLL Loading" work into dev_phase.
This work was already reviewed in PR #37 when "DLL Loading" was written against dev-miniapp.

[github-actions]

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• Other pull requests
• Contribution Guidelines - Contributing Overview