Introduce an encapsulation of the various elements of the management mod...

...el

Use it support the copy-on-write/publish-on-commit semantic for ops that make management model changes

This is foundational work toward the capability/requirement stuff, which will use this new ManagementModel interface to handle the copy-on-write/publish-on-commit semantic for changes to the registry of capabilities/requirements.
I think we could remove this deprecated method, given that new test frame work properly isolates / delegates classloader to legacy classes.
@kabir wdyt?