Feature request: a `run` mutation

[ZacSweers]

While there are a number of mutations today for defining scenarios, we've found them unhelpful in some cases due to either being too trivial or too limiting. I'd like to propose a new run mutation that would act similar to git bisect run, where an arbitrary shell script + any arguments is given. This would be invoked before each iteration to apply a set of changes handled by the script.

One example where we would want to use this is to apply changes that would specifically change the dependency graph in a build profiling Dagger, such as adding a parameter to an injected class's constructor. This would give flexibility for scenario authors to profile specific cases unique to their build.

[ZacSweers]

If you're open to this, I'd gladly look at contributing a PR for this

[wolfs]

@ZacSweers Is this PR more or less what you are looking for? #310

[ZacSweers]

Yup that's exactly what I'm looking for 👍