[cleanup] Rename type ID in Move Framework to VersionedID

[666lcz]

Per discussion in #291, VersionedID is an more appropriate name because the struct contains both the id and version.

[sblackshear]

Excellent, thanks for taking this on! This unblocks some other improvements I'd like to see in ID:

• Changing get_id to return an &ID instead of a VersionedID--getting a stable ID is likely what folks want in the common case, not an unstable VersionedID
• Moving IDBytes to a different module--I think this will allow us to fix a lot of the horribly confusing naming (that I am responsible for, apologies) of functions that return ID vs IDBytes
• We could consider rearranging the API's to prevent Move programmers from reading the version altogether... it's not used by any application code right now, and writing code that reads the version is bound to be hard for tools like the Move prover to reason about because the logic for updating it lives in the adapter. In addition, the new testing code doesn't mock versions (and it would be tricky to change it to do so), so this change would also prevent folks from writing tests that won't work.

One final note If you don't mind, I would appreciate if you don't land this until I can get #490 in, since it is blocking some future testing + tutorials.

[sblackshear]

#490 is in--sorry for the conflicts!