support encrypting/decrypting non-yaml files used with --set-file

[sshucker]

No description provided.

[sshucker]

Please let me know if you'd like secrets.sh refactored to rename the $yml variable since this will no longer be exclusive to yaml files. I figured a reviewer would either

1. really want that renamed
   or 2) get really annoyed at the size of the refactoring to rename it.
   So if you want it renamed, I'd prefer to do that as a second commit on the same PR

My use case for this is using --set-file to expose a gpg keyring through a helm secret that will be mapped to the container's filesystem

[anton-chuhunou]

Please merge this merge commit. I also need this functionality