feat: support config env expansion

[raffis]

Current situation

Using an .actrc config it is not possible to utilize envs as there is no env expansion since its not invoked from a shell.

I'd like to have a config like this which is currently not working:

--detect-event
-s GITUB_TOKEN=$GITHUB_TOKEN
-s GH_ACTIONS=$GITHUB_TOKEN
--container-options --privileged --mount type=bind,source=/home/$USER/.docker-act,target=/home/runner/.docker

Proposal

Expand any envs while appending the caller args.

[ChristopherHX]

I think this is useful, but another maintainer or the owner need to decide

[codecov]

Codecov Report

Attention: 872 lines in your changes are missing coverage. Please review.

Comparison is base (4989f44) 61.22% compared to head (9a7d7fc) 61.64%.
Report is 288 commits behind head on master.

Files	Patch %	Lines
pkg/artifactcache/handler.go	65.46%	102 Missing and 42 partials ⚠️
pkg/runner/run_context.go	73.37%	75 Missing and 19 partials ⚠️
pkg/runner/expression.go	55.17%	66 Missing and 12 partials ⚠️
pkg/runner/action_cache.go	50.74%	49 Missing and 17 partials ⚠️
pkg/container/docker_network.go	0.00%	56 Missing ⚠️
pkg/container/docker_run.go	2.00%	48 Missing and 1 partial ⚠️
pkg/model/workflow.go	43.37%	40 Missing and 7 partials ⚠️
pkg/common/outbound_ip.go	0.00%	44 Missing ⚠️
pkg/container/host_environment.go	0.00%	43 Missing ⚠️
pkg/artifactcache/storage.go	60.22%	24 Missing and 11 partials ⚠️
... and 25 more

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2063      +/-   ##
==========================================
+ Coverage   61.22%   61.64%   +0.42%     
==========================================
  Files          46       53       +7     
  Lines        7141     8808    +1667     
==========================================
+ Hits         4372     5430    +1058     
- Misses       2462     2948     +486     
- Partials      307      430     +123     

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[wolfogre]

LGTM. I don't see any reason why users would want to keep the original string $XXX in args. If they do, they can use $$XXX.

[ChristopherHX]

What happended here?
mergify pushed, then the pr owner pushed a few seconds later? Or is that a GitHub bug.

[mergify]

@raffis this pull request has failed checks 🛠