Consider including a locale, as well as given name and surname, in PersonName

In the discussion on [PR#215](https://github.com/adobe/xdm/pull/215) @trieloff proposed that we consider including both a locale and givenName, surname fields in addition to the firstName, lastName, and fullName added for #215.

## What are the schemas that are affected by the issue
schemas/context/person-name.schema

## What are examples of products that are impacted by the issue
Experience Cloud

Start with schemas/context/person-name.schema and review PR#215 to understand the existing firstName, lastName, and fullName fields. Determine the intended locale, givenName, and surname additions for the Experience Cloud impact described; done means the affected schema clearly represents the agreed fields and their definitions.

Written by the indexing model from the issue text.