NFT media properly categorized

We've improved the way we categorize NFT media in our [List Media](https://docs.center.dev/reference/listnftmedia-v2) and [NFT Metadata](https://docs.center.dev/reference/shownftmetadata-v2) responses.

We've improved the way we categorize NFT media in our List Media and NFT Metadata responses. This gives our users much more visibility into exactly what types of media are available for each NFT. We also provide mime type for each, so our users can make a much more informed decision about what they want to render and how.