(MODULES-4275) Customize ACE YAML serialization

[Iristyle]

• Ruby 2.3 has changed the behavior of YAML serialization so that
  Hash derived instances will serialize all of their instance
  variables per:

  ruby/ruby@fe0414b

  Psych used to produce an empty serialization of the ACE type in
  Ruby 2.1.9 like:

   --- !ruby/hash:Puppet::Type::Acl::Ace {}

In Ruby 2.3, it will produce something like this:

   --- !ruby/hash-with-ivars:Puppet::Type::Acl::Ace
     elements: {}
     ivars:
       :@provider:
       :@identity: Administrators
       :@hash:
       :@id: S-32-12-0
       :@mask: '2023422'
       :@rights:
         - :full
       :@perm_type: :allow
       :@child_types: :all
       :@affects: :all
       :@is_inherited: false

The issue that arises is that @Provider is a Puppet provider
instance that cannot be YAML serialized and will crash in 2 key
situations during a Puppet run:

* When the last_run_report.yaml is persisted
* When corrective changes transaction reports are written

• The solution is to implement the encode_with method on the ACE type
  to control what gets serialized. Since ACE already has a to_hash
  method, let it do the heavy lifting to produce the bare Hash
  structure for Psych to serialize.

  Note that nil is passed as the "tag" used by Pysch, which means
  that the key / value pairs are emitted as a bare YAML hash instead
  of the custom type:

    --- !ruby/object:Puppet::Type::Acl::Ace

• This should also more correctly fix a longstanding PE console issue
  described in PCP-542 where the master is unable to deserialize
  YAML strings like the following because the Ruby classes are not
  loaded on the master:

   !ruby/hash:Puppet::Type::Acl::Ace {}

• Also see PUP-7381 for other YAML serialization work proceeding
  within Puppe to address Ruby 2.3 related behavioral changes.

[joshcooper]

@glennsarti what's the earliest branch this should be targeted at?

[Iristyle]

This change will be backwards compatible with older Puppets, so the course of action depends on release plans I think. This could plausibly be a 1.1.3 or 1.2.0 that maintains the same compatibility that it currently does.

There is another ticket that needs to be tackled for Puppet 5 that will break backwards compatibility - https://tickets.puppetlabs.com/browse/MODULES-3093. It will require a major version bump to ACL 2.0 and will require a minimum Puppet version of 4.4 I believe.

[glennsarti]

@joshcooper I'm not the best person to answer the targetting question.

[glennsarti]

From conversation. This should target master