implement `secretspec export`

[danielgafni]

I need to use secretspec from:

• containerized pipelines (Dagger)
• GitHub Actions

Both use cases imply I can't do secretspec run, instead, I would like to first invoke secretspec to fetch the secrets and prepare the environment for other tooling.

I believe this could be achieved by a new secretspec export command. It could take a --format argument, taking shell (default, so eval $(secretspec export) just works), dotenv, json, and gha (for env masking in GitHub Actions) options.

How does it sound @domenkozar ?

For reference, this is what --format gha would output:

::add-mask::very-secret
export DB_PASSWORD=very-secret

secretspec export --format gha could be used to build an official GitHub Action on top of it.

[domenkozar]

Sounds great!