(MODULES-10874) Add property 'sync'

This property controls how transactions are synchronized and it has been
available since Solaris 10 8/11 release:

https://docs.oracle.com/cd/E26505_01/html/E37384/gbscy.html#gjzl

REFERENCE.md

@@ -146,6 +146,10 @@ The sharesmb property. Valid values are `on`, `off`, sharemgr(1M) options
 
 The snapdir property. Valid values are `hidden`, `visible`.
 
+##### `sync`
+
+The sync property. Valid values are `standard`, `always`, `disabled`.
+
 ##### `version`
 
 The version property. Valid values are `1`, `2`, `3`, `4`, `current`.

lib/puppet/provider/zfs/zfs.rb

@@ -84,7 +84,7 @@ Puppet::Type.type(:zfs).provide(:zfs) do
    :mountpoint, :nbmand, :primarycache, :quota, :readonly,
    :recordsize, :refquota, :refreservation, :reservation,
    :secondarycache, :setuid, :sharenfs, :sharesmb,
-   :snapdir, :version, :volsize, :vscan, :xattr].each do |field|
+   :snapdir, :sync, :version, :volsize, :vscan, :xattr].each do |field|
     define_method(field) do
       zfs(:get, '-H', '-o', 'value', field, @resource[:name]).strip
     end

lib/puppet/type/zfs.rb

@@ -136,6 +136,10 @@ module Puppet
       desc 'The snapdir property. Valid values are `hidden`, `visible`.'
     end
 
+    newproperty(:sync) do
+      desc 'The sync property. Valid values are `standard`, `always`, `disabled`.'
+    end
+
     newproperty(:version) do
       desc 'The version property. Valid values are `1`, `2`, `3`, `4`, `current`.'
     end