Use pre-generated RSA keys for signing packages

[PhoenixMage]

Keys are stored as Repository secrets within Drone.
An environment statement similar to the below would need to be added to the build step of the aports .drone.yml:

  environment:
    PKG_SIGN_KEY:
      from_secret: pkg_sign_key

The secret within the drone console would be named pkg_sign_key and would contain the multiline RSA key you want to use such as from ~/.abuild/.rsa

This would allow adding a step to upload the package post build such as to an AWS S3 container or via scp to a filestore so it can be used on your own systems that container the corressponding public key.

If the required configuraion doesnt exist it will revert to previous behaviour and auto gen keys on build.