Add Do and DoSync runners

[groovemonkey]

Overview

Change the runner interface so Run returns a collection of ops.
Products store the results of these ops under the id of the runner.

Add “do” runner that can accept a list of runners and calls .Run() on each in a goroutine.
Return all results as []op.Op
We’ll need to change the runner return to []op.Op

Add “do-sync” runner that can accept a list of runners and calls .Run() for each in order.
Check the Status of the result op and if it’s not Success, abort returning all existing ops.

Notes

• runners don't currently log. that breaks logging -- to get around this, I'm passing the product logger (which is really the agent logger) into Do/DoSync.

• Host and nomad runners run inside of a Do runner (async): return []runner.Runner{runner.NewDo(l, runners)}

• I've written this intentionally so that Do and DoSync can be nested -- it ain't pretty, but it's fine:

// runners := []runner.Runner{} // whatever product runners you start with
syncRunners := []runner.Runner{
runner.NewCommander("uname -a", "string", cfg.Redactions),
runner.NewCommander("echo foobar", "string", cfg.Redactions),
}
// Execute asynchronously: Do inside of DoSync
allRunners := []runner.Runner{runner.NewDoSync(l, append(syncRunners, runner.NewDo(l, runners)))}
return allRunners, nil

• Do/DoSync runners could add their own "Op" result to the end of the op-slice they return from all their runners implemented in dosync.go). Is that how we want to do this?

[nwchandler]

Since the map isn't needed until we have the lock, an alternative way (not sure it's better or worse, but it avoids a variable assignment) would be to do something like (*sm)[ridx] = o after the lock.

[mkcp]

Just realized I forgot to actually approve the branch, as discussed. Dave and I have working on this together and have iterated through two approaches for returning collections of results. Constraining Op.Result to a map[string]any allows us to build around nested trees of ops, and was easier to work with than []op.Op. do.Do and do.Sync leverage the results changes to return their result with multiple ops, and each previous runner has been changed to return results in a semantic key.