Allow providing ec2-instance-count to start multiple runners

[dexbleeker]

Fixes #8

This PR is based on the fork of @messense, specifically this commit.

It allows for providing ec2-instance-count as input variable and will start multiple runners if desired. By default 1 runner is started.

Note that this might not be the cleanest code or best implementation. I don't write JS generally and have not touched a GH action before. Especially Array.from(JSON.parse(ec2InstanceIds)) feels wrong.

All feedback is welcome however.

[mickmorse]

Works like a charm

@machulav 👀

[mickmorse]

Only comments are to update the readme surrounding the outputs and examples (with it now being ec2-instance-ids)

[wu-json]

Any plans to merge this?

[Dmitry1987]

MinCount/MaxCount are not used anywhere, shouldn't it be a specific count, why there's a min/max, kind of "if at least N will successfully be created" ? a useful feature for me too, i wonder why won't be merged :(

[thimios]

+1 Very useful feature for us too.