cephadm: drop deploy_arguments key from deploy config JSON

cephadm: drop deploy_arguments key from deploy config JSON

Drop the now unnecessary deploy_arguments subsection from the JSON
object that the new `_orch deploy` takes. The intermediate code that
used it in the ceph mgr module has been replaced with `params`.

We still want to share some code with the old deploy, especially the
default values for various things that get attached to `ctx`. In
some cases this is particularly important as not all code checks
that `ctx` has an attribute first. Create an `ArgumentFacade` type
to reuse the `add_argument` calls for deploy, and instead store the
default key-value pairs for `ctx`.

Signed-off-by: John Mulligan <jmulligan@redhat.com>