Feature request: Add private/public key options to RSA Encryption/Decryption

The existing RSA Encrypt/Decrypt options only allow a public or private key respectfully.
Please add the option to use a private key when encrypting, and a public key when decrypting.

An example is https://www.devglan.com/online-tools/rsa-encryption-decryption
That website allows you to select a public or private RSA key for both operations.

Review CyberChef's existing RSA Encrypt/Decrypt options and compare their current key restrictions with the behavior described in the issue. Use the linked RSA example as a reference; done means both operations allow selecting either a public or private RSA key, with the existing encryption and decryption behavior preserved.

Written by the indexing model from the issue text.