Use graalvm native image without libsodium

[brunovg]

We used a custom graalvm base image with libsoudium, mainly because we had (on 4.15.x) the possibility of reverting to the old backend, where libsodium was already used to encrypt/decrypt tenant variables.

On 4.17.x it's not possible anymore.

What needs to be done:

• use the initial backend (Assimbly) code, that uses a more recent type of encryption;
• change ruby on rails code to use the same type of encryption;
• migrate mongodb tenant variables that are encrypted, to use the same type of encryption.