This method creates a folder for emails in the project and returns it with the same fields as Get the list of folders.
The returned id can be passed as folderId to Generate an email, Create an email from MJML, Create or overwrite an email from HTML, Copy emails into a folder and Move emails into a folder.
The folder appears in the project in Stripo right away. It has no author, the same as emails created through the API.

Folder name rules:

• up to 100 characters;
• must not contain [ ] { } $ < >;
• if an email folder with the same name already exists in the project, a number is added (e.g. Offers 2); the response contains the actual name.

The number of folders in a project is limited, the same as in Stripo.