feat: upload and delete files

[EstebanBorai]

First implementation on the ImageKit client with support for uploading
tokio::fs::File instances and also removal (delete) files from the File Storage
given the file id.

---

Working example:

use imagekit::ImageKit;
use imagekit::delete::Delete;
use imagekit::upload::types::FileType;
use imagekit::upload::{Options, Upload, UploadFile};
use tokio::fs::File;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut image_kit = ImageKit::new(
        "your_public_api_key",
        "your_private_api_key",
        "https://ik.imagekit.io/your_imagekit_id/",
    );

    // Upload an image from File
    let file = File::open("assets/ferris.jpeg").await.unwrap();
    let opts = Options::new(upload_file, "ferris");
    let upload_result = imagekit.upload(opts).await.unwrap();

    // Delete a file
    let delete_result = imagekit.delete(upload_result.file_id).await;
}