feat: allow compute on handle allowedForDecryption

[immortal-tofu]

If we allow compute on ciphertext tagged as "decryptable" it would allow the possibility to have ciphertext "public" and used by anyone. For example, if a view function needs to return a default value, we could store it and returns it. This default value would be usable by any contract getting it.

It would mean This function should verify allowedForDecryption