Add support for Create a file upload

[KoditkarVedant]

Use this API to initiate the process of uploading a file to your Notion workspace.

For a successful request, the response is a File Upload object with a status of "pending".

The maximum allowed length of filename string is 900 bytes, including any file extension included in the file name or inferred based on the content_type. However, we recommend using shorter names for performance and easier file management and lookup using the List file uploads API.

https://developers.notion.com/reference/create-a-file-upload

[BrettPost]

Hey @KoditkarVedant, I was interested in taking this on today, but I see that you just assigned it to yourself. I was going dive into all of these API file issues. Are you wanting help with these still?