Bundle custom i18n translations with extensions

Summary Although extensions can use _existing_ i18n translations, there doesn't seem to be a good way to define new custom translations that get loaded with the extension. This would be especially useful for app and hybrid extensions with interface fields so that translations could be used for field labels, field notes, and other custom UI text. For example, built-in operations use translations to [define an operation's name and description]( and it'd be great if extensions could do this, too. Basic Example When an extension is loaded, load translations/*.yaml from the extension package the same way Directus loads its built in translations. Motivation Directus is a Multilingual App which supports full internationalization. However, extensions cannot currently leverage Directus's i18n system to its full capacity. Detailed Design Update the create-directus-extension tool to copy src/lang/translations/*.yaml to the dist folder upon build. Mo…