Support localized tag attribute

[ahayes]

The tag attribute type was added to schema definitions through issue #987 and support was added to the schema builder tool via issue #1097.

Now that some multilingual atlases are using tag attributes in schemas, we need to add support for localized tag attributes.

The changes to definition.json syntax to support this will require a bit of thought to end up with a consistent approach given the existing localized attribute type and array elementType already in use. The Schema Builder tool should also be adjusted as required to support the changes.