Add methods to `resource::Metadata` that accept `common::Managers`.
- Now, create, read, and write functors should accept a shared pointer
to
smtk::common::Managers
as their last argument. - Operations now accept a Managers instance, which is configured by the operation manager upon creation of the operation.
- This also changes the API of
smtk::project::Metadata
to accept the newcreate()
signature. - We now provide a
smtk::resource::json::Helper
class that provides access to the managers. It is configured by Read operations to pass the Managers instance given to the operation.