Refactor resource discovery code

[SteveL-MSFT]

PR Summary

In preparation to add support for handle multiple and finding specific versions of resource, needed to refactor the existing code.

• New helper to simply find all command based resources
• Another helper to enumerate adapter resources
• All the discovery is cached in memory
• Rename discover_resources() to be find_resources() as that's really what it does based on a filter
• Functions now return a vector of resources of the same type name, but different versions

Because the changes moves around lots of existing code, might be easier to review the file rather than the diff.