(maint) Migrate rsync_* into Pkg::Util::Net

This PR migrates the rsync_to and rsync_from methods from 00_utils
into Pkg::Util::Net. 00_utils now has deprecations for rsync_to and
rsync_from and will automatically dispatch to the new methods. The new
methods have an explicit parameter list, which was already being used in
all instances in packaging. As it is being moved from rake to pure ruby,
ex is used instead of sh in the invocation. Existing invocations are updated
to the Pkg::Util::Net versions.
The PR also includes some minor improvements to remote_ssh_cmd.