Allow running multiple Leeway scripts in parallel about leeway

[csweichel]

Both options (inter-script dependencies and multiple args to run) are nicely orthogonal. Given the very low complexity of enabling run <script1> <script2>, and the nice affordance this produces, this is the way.

We would want to note in the long description of the run command that multiple scripts will be executed in parallel.

[meysholdt]

I like the simplicity of passing multiple scripts to leeway run.

How would you format logs?
Would there be an additional level of [xx] prefixes on top of the ones our nested call of leeway build already generates?
E.g. leeway run dev/preview:create-preview dev/preview:build would output

[dev/preview:build][component1] Building....
[dev/preview:build][component2] Building....
[dev/preview:create-preview] Terraform init...
[dev/preview:build][component2] Building....
[dev/preview:create-preview] Terraform apply...

When we discussed parallelism in the past, I did have another solution in mind: Make the executable element part of the build graph, so Leeway could decide parallelism based on dependencies, just like it does with packages today. However, if we can get away with a simpler solution, I'm all for it.

[csweichel]

Would there be an additional level of [xx] prefixes on top of the ones our nested call of leeway build already generates?

I would not think so.
There is the opportunity for one harmonised build beforehand though, i.e. instead of building many different _deps packages, build one single one.