Overview

What does this pull request do? changes entityType and entitySubtype from 2 separate fields into one object. Updates test files and example files.
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Translations

[ ] New or edited strings appearing as a result of this PR will be picked up for translation
[ ] I've notified the translation coordinator of any new strings that will need translating. See: https://openownership.github.io/bods-dev-handbook/translations.html

[ ] I've checked that the documentation builds without failing. See: https://github.com/openownership/data-standard#building-the-documentation-locally
[ ] I've thought about how and when this needs to be released. See: https://openownership.github.io/bods-dev-handbook/standard_releases.html
[ ] I've updated the changelog, if necessary.
[ ] I've updated reference.rst to reflect any changes to schema structure or naming.
[ ] I've added or edited any other related documentation. See: https://github.com/openownership/bods-dev-handbook/blob/master/style_guide.md