Support additional setup in ruby pipelines

[ryanwi]

use case is a Ruby app that also needs python setup.

[Null-Is-Null]

This will work, but that use of eval doesn't feel good from a security perspective. I know impact will be limited since this is running on a runner and will only be used internally, but what if we standardized on something like a ci-bootstrap.sh script that lives in the target ruby repo that gets run if present? I'm fine with proceeding with the approach in this PR for now if that's preferable.

[ryanwi]

use of eval

isn't that what we're already doing here? https://github.com/signalwire/actions-template/blob/main/.github/actions/test-ruby/action.yml#L121

[Null-Is-Null]

After reviewing the lines you linked I realize we probably shouldn't be doing that there either. That's not exactly the same as an eval but is effectively executing commands passed as a string with some checks in place (seeing if the command starts with bundle). Approving for now since potential impact is limited as described in prior comments.

[ryanwi]

That's what I thought you'd say :-)