feat(action): allow passing arguments to docker container

[coralinepetit]

Why

Using packer-github-action I would like to be able to to pass arguments to my container (such as mountpoints)

How

Follow Github actions docs to add and args option to the run dockerfile

[hashicorp-cla]

All committers have signed the CLA.

[ksatirli]

Hi @coralinepetit,

Thank you for the proposed changes - we understand the need to specify custom arguments and @JenGoldstrich and I are working on ways to make this possible by providing a more direct interface to the packer binary (and the ability to specify arguments)

I'm going to close this PR for now and encourage you to follow along in the main branch, which we will shortly release new changes on.