Add functions to get and set full Item metadata

[rkoshak]

The current set of functions only work with metadata values, not full metadata with a value and configuration map. This is a feature request top add functions that will get, insert, upsert, delete full metadata entries.

[digitaldan]

Have you seen #43 ? We were discussing moving out meta data to its own namespace and then adding missing functionality . I have not circled back to finish that up yet.

[rkoshak]

I did not see 43. I looked at the issues but not the active PRs. I'll close this since it looks like it's being addressed.