Setup GitHub actions to plan/apply terraform config

[arvindpunk]

Use GitHub Actions to do the following:

1. CI/testing (equivalent to terraform plan) on each non-master commit
2. Deployment (terraform apply) on each master commit/push

Required environment variables will be set as GitHub Actions secrets by repository owners when merging the PR for this.

edit: Split deployment into a different issue #2.

[akshatagarwl]

@arvindpunk Possible to break this task down? Might make it easier for someone who's new to GA & Terraform to pick this up

[glokta1]

hello! I'd like to work on this

[akshatagarwl]

@glokta1 Awesome. LMK if you need any help in breaking this task down further if you have any trouble figuring where to start.

[glokta1]

Hi, is this the relevant documentation?

[arvindpunk]

@glokta1 Yes, that seems like exactly what we need (maybe except the commenting errors part, that's a bit overkill). Do let me know if we need to add any other secrets, I'll add them.