cliconfig improvements

[bashbaug]

Description of Changes

This PR includes several minor updates to the cliconfig configuration utility:

• When dynamically loading OpenCL.dll to query platform and device information, load the DLL from system32 unconditionally. While OpenCL.dll can legitimately exist somewhere else, it will be in system32 in most configurations, and this will prevent loading some other OpenCL.dll inadvertently.
• Clean up, unify, and modernize the handling of platform and device information, especially in error conditions, such when the OpenCL.dll cannot be loaded.

Testing Done

Tested on a system with multiple platforms and devices, both when the DLL can be loaded and when it cannot (tested by trying to load some other DLL name instead of OpenCL.dll). Observed graceful error behavior when the DLL cannot be loaded or when an index is out-of-range.