feat(str): add datasource for encrypting a string

[kaizensparc]

Context

I'm using providers that give me access/secret keys that I need to send to ansible after they're generated. My goal is to encrypt these keys before I write them in my group_var templates. This should help #124. For my use case, I use a template to write the group_vars.

Before creating my pull-request, I ensure:

• [x] Documentation is written
• [x] Unit tests are written and green
• [x] I've cleaned my WIP or meaningless commits
• [x] Examples are up-to-date