Load events from .csv or .json files

[Oscar-gg]

Implement the option of creating multiple events by loading a .csv file or .json file.

Implementation Idea:

• Let the first line of the .csv file be a list indicate which fields are provided in subsequent lines.
• If a .json file is provided, parse each entry with a zod schema and add successfully parsed events to the database, if the required permissions are available. If any event isn't parse correctly, display explanation and don't add any event.
• If a .csv file is provided, transform it to a .json or object directly, and the parse it and follow the same procedure as above.
• Add confirmation windows when loading events and a preview of the events added.