fix: AWS deployment system

[cherriechang]

by migrating to AWS SDK

[becky-gilbert]

While reviewing/testing this, I came across a few other issues that I've fixed here (sorry - in the future they will go in separate, smaller PRs!).

Here's a summary of the changes since my last comment:

• Merged branch that fixes several worker issues (fix: experiment workers not set up in pushkin-cli currently #376) and fixed merge conflicts.
• Merged branch that fixes error in pushkin prep when no experiments are installed (check for .yalc/ and yalc.lock, and create these if needed #406)
• Await execFile commands in try/catch blocks to catch/handle async docker errors.
• Update the worker index.js files for non-basic experiment templates to match the basic template.
• Update SSL check logic so that this only sets SSL: true for RDS endpoints (no SSL for any non-RDS host names, not just localhost)
• Await logTransaction in pushkin worker to prevent race condition that causes data-saving errors
• Fix a TypeError that can occur in the catch block for docker database set-up errors. This TypeError was masking the actual error that should be reported to the user.
• Udpate ensureCleanState in pushkin prep so that it handles orphaned pushkin DB volumes. (Previously it would detect containers and then remove everything, but the container check misses the case when containers were removed but volumes remained - this would cause pushkin prep to fail in the same way that it would before with existing containers).
• Add/update changesets (not actually sure if this is necessary because the changesets should describe fixes relative to the last release, and some of these changes might be just fixing bugs within this branch...).

@cherriechang if you're happy with all of this then we're ready to merge! Otherwise let me know if you have feedback/questions - happy to make changes.

[becky-gilbert]

🚀