MONGOID-4823 Values for BSON::Binary fields are not converted to Binary (#5317)

* MONGOID-4823 add (de)mongoize for Binary

* MONGOID-4823 add tests for ObjectId

* MONGOID-4823 add release note

* MONGOID-4823 fix comment

* MONGOID-4823 answer comments

* MONGOID-4823 use ::BSON

* Revert "MONGOID-4823 use ::BSON"

This reverts commit 5c893e93562b9d3855adaa8411a4d35e0455fd31.

* MONGOID-4823 revert back to without ::BSON

* MONGOID-4823 fix document test

Author: neilshweky

source/release-notes/mongoid-8.0.txt

@@ -447,3 +447,28 @@ For example:
 
 As you can see from this example, after pushing ``user2`` to the users array,
 Mongoid 8 correctly updates the number of elements without requiring a reload.
+
+
+Repaired Storing Strings in BSON::Binary fields
+-----------------------------------------------
+
+In Mongoid 8, storing a String in a field of type ``BSON::Binary`` will be
+stored in and returned from the database as a ``BSON::Binary``. Prior to Mongoid 8
+it was stored and returned as a String.
+
+.. code::
+
+  class Registry
+    include Mongoid::Document
+    field :data, type: BSON::Binary
+  end
+
+  registry = Registry.create!(data: "data!")
+  p registry.data
+  # => Mongoid 7: "data!"
+  # => Mongoid 8: <BSON::Binary:0x2580 type=generic data=0x6461746121...>
+
+  registry = Registry.find(registry.id)
+  p registry.data
+  # => Mongoid 7: "data!"
+  # => Mongoid 8: <BSON::Binary:0x2600 type=generic data=0x6461746121...>