Deprecate the rsync/ssh mover

[JohnStrunk]

Describe the feature you'd like to have.
The rsync/ssh mover's functionality will be replaced by an equivalent mover that uses rsync/stunnel to send the data over a TLS/PSK transport instead of ssh.

What is the value to the end user? (why is it a priority?)
The rsync/ssh mover requires additional capabilities that make it incompatible with the PSS/Restricted security level. In order to provide better cluster security, this mover should be deprecated in favor of an stunnel-based one.

How will we know we have a good solution? (acceptance criteria)

• Provide a multi-stage deprecation over several releases:
  1. Post an event telling users to switch to the new mover
  2. Require the Namespace annotation Support a Namespace annotation indicating elevated privileges are ok for movers #365 in order to use this mover, and if missing, expose that in the RS/RD Syncing status condition
  3. Remove the rsync/ssh mover. There is no rush on actual removal as the Namespace annotation requirement will be sufficient to wall it off

Additional context

• Depends on Create a new rsync-based mover that uses stunnel w/ PSK instead of ssh #364

[JohnStrunk]

#516 adds a note to the rsync-ssh docs that users should move to rsync-tls

[JohnStrunk]

Proposed schedule:

• release-0.7 ➡ Post event to encourage migration
• release-0.8 ➡ Require Namespace annotation