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

从所引用行的 AccountType.java 开始，然后将其中的类型和措辞与 Dropbox 套餐页面及 users/get_account API 文档进行比较。确定不匹配属于 API 还是 SDK 文档，并在账户类型和描述与所引用来源保持一致地反映其内容时视为工作完成。

由索引模型根据 Issue 内容生成。