Incomplete and non coherent account type enum

The types and wording in `AccountType` [^1] does not reflect the available plans advertised [^2]. This is probably an issue with the API itself [^3] but would at least require updated documentation.

[^1]: https://github.com/dropbox/dropbox-sdk-java/blob/e8b39d1f8e6ea81b6c547ae8e66a47eb0e7be40b/dropbox-sdk-java/generated_stone_source/main/src/com/dropbox/core/v2/userscommon/AccountType.java#L22C1-L35
[^2]: https://www.dropbox.com/plans
[^3]: https://www.dropbox.com/developers/documentation/http/documentation#users-get_account