Support condensed virtual_attribute definitions

I'm trying to guage what people think of this new syntax.

1. It has the ruby and sql definitions together rather than scattered.
2. It has 2 blocks (arel and ruby) back to back.
3. It auto generates the "use attribute from select()" line. i.e.:

   return self["archived"] if  has_attribute?("archived")
   

4. The "use attribute if from select()" is missing all over our code, so that is a win.
5. The ruby method will be defined using metadata rather than ruby. (something to be said for plain old ruby)
6. This can be added incrementally.

NOTE: If you look in the code, the t.grouping() adds parens around the SQL. This is no longer necessary and going through this will allow us to remove it.

Before

  def archived?
    return self["archived"] if  has_attribute?("archived")

    ems_id.nil? && storage_id.nil?
  end
  alias_method :archived, :archived?

  virtual_attribute :archived, :boolean, :arel => (lambda do |t|
    t.grouping(t[:ems_id].eq(nil).and(t[:storage_id].eq(nil)))
  end)

After

  virtual_attribute :archived, :boolean, :arel => -> (t) {
    t[:ems_id].eq(nil).and(t[:storage_id].eq(nil))
  } do
    ems_id.nil? && storage_id.nil?
  end
  alias_method :archived, :archived?

Before 2

class VmOrTemplate
  def normalized_state
    return self["normalized_state"] if has_attribute?("normalized_state")

    %w[archived orphaned template retired disconnected].each do |s|
      return s if send(:"#{s}?")
    end

    power_state&.downcase || "unknown"
  end

  virtual_attribute :normalized_state, :string, :arel => (lambda do |t|
    Arel::Nodes::Case.new
      .when(arel_table[:archived]).then(Arel.sql("'archived'"))
      .when(arel_table[:orphaned]).then(Arel.sql("'orphaned'"))
      .when(t[:template].eq(t.create_true)).then(Arel.sql("'template'"))
      .when(t[:retired].eq(t.create_true)).then(Arel.sql("'retired'"))
      .when(arel_table[:disconnected]).then(Arel.sql("'disconnected'"))
      .else(t.lower(t.coalesce([t[:power_state], Arel.sql("'unknown'")])))
  end)
end

After 2

class VmOrTemplate
  virtual_attribute :normalized_state, :string, :arel => -> (t) {
    Arel::Nodes::Case.new
      .when(arel_table[:archived]).then(Arel.sql("'archived'"))
      .when(arel_table[:orphaned]).then(Arel.sql("'orphaned'"))
      .when(t[:template].eq(t.create_true)).then(Arel.sql("'template'"))
      .when(t[:retired].eq(t.create_true)).then(Arel.sql("'retired'"))
      .when(arel_table[:disconnected]).then(Arel.sql("'disconnected'"))
      .else(t.lower(t.coalesce([t[:power_state], Arel.sql("'unknown'")])))
  } do
    %w[archived orphaned template retired disconnected].each do |s|
      return s if send(:"#{s}?")
    end

    power_state&.downcase || "unknown"
  end
end