Per-repo configuration

[prologic]

Now that #74 is completed, merged and working nicely (for the most part) we need a way to be able to write configuration on a per-repo / project basis and read from this.

Right now you can override the platform via the -P flag. This is great! It would be even better if a repo owner could define this in an .actrc config file in the top-level directory of the repo which would let us customize the way act behaves on a per repo / project basis.

  -P, --platform stringArray   custom image to use per platform (e.g. -P ubuntu-18.04=nektos/act-environments-ubuntu:18.04)

It would be equivalent of running (by hand):

act -P ubuntu-latest=nektos/act-environments-ubuntu:18.04

Even better would be to recursively search for and read .actrc so you can define a per-repo scoped configuration and if none exists default to a global one. I'm open to either just reading one defined in the default configuration location too if none exists in the repo.

This would let me do a few things:

• create a set of custom images that our workflows need so we can substitute automatically (by repo .actrc configuration) the runner used in our workflows
• let our developers just run act to run the same GHA workflows defined as-is without having to think about it

[prologic]

Ahh you beat! I'll test this out in the nxt days and let you know how it all goes! I'll file any other issues that creep up or improvements that are needed. My end goal of course being "Be able to run workflows locally".