Add Ability to access orgs through JWT

[Julian88Tex]

Currently, you need an access token to access an org which is only given for persistent orgs (production, sandbox, etc.) and no scratch orgs. It would be nice to be able to access scratch orgs through JWTs.

Ideally, this would be similar to the process described in this Trailhead module: https://trailhead.salesforce.com/en/content/learn/projects/automate-cicd-with-gitlab/integrate-with-gitlab

[brianevanmiller]

There are a couple working examples of using JWT in Github actions:

1. Salesforce Continuous Integration with GitHub Actions - nice yml snippet using JWTs
2. How To Use Existing SFDX CLI Action From the Github Marketplace For Your Salesforce DX CI - Deep dive video