Auto-locate and inject matching secrets as needed

[aaronsteers]

Originally tracked in #1

Secrets management Phase 2. Auto-detect and inject

In this phase, presumably we'd be able to auto-inject secrets if they match a specific naming convention that aligns with the source name and setting name.

Tech Spec here:

https://docs.google.com/document/d/1rqoRuGRDvSYX8TmtxvpJv-XJgzfN46fLYtuMymz-QE8/edit#heading=h.c4ztxwwo0ign

Re: Priority

We can probably postpone/deprioritize this one for a little while. It will be most valuable we want the same secret value to be applicable from both local and hosted execution models.

[bindipankhudi]

To be done prior to #33