Organize nupkgs for publishing

[surajkrishnan14]

Description

This change:

• Modifies the post-build script to copy the unsigned nupkgs to the packages subdirectory under build\bin\<arch>. This directory is monitored by internal pipelines to publish nuget packages.
• Updates the name of the core package to include the configuration in the generated name, for non-release configurations. eg. eBPF-for-Windows.x64 for the "NativeOnlyRelease" configuration and eBPF-for-Windows.x64.NativeOnlyDebug for the "NativeOnlyDebug" configuration.
• Updates the name of the SDK package to include the architecture in the generated name. Similar to the core package, it may also include the configuration for non-release configurations. eg. eBPF-for-Windows-Redist.x64 or eBPF-for-Windows-Redist.x64.NativeOnlyDebug

Testing

Internal pipelines were run and confirmed to publish the packages as expected