Create admin API key for development stack

[KrishnaIyer]

Summary

Create admin API key for development stack

Changes

• Add option to create an API key for the admin user for dev:initStack.
• Update doc

Testing

• Rebuild mage (make init)
• Run $ tools/bin/mage dev:initStack
• Copy generated API key and try with CLI.

Regressions

NA

Notes for Reviewers

Run $ make init for this.

Checklist

• Scope: The referenced issue is addressed, there are no unrelated changes.
• Compatibility: The changes are backwards compatible with existing API, storage, configuration and CLI, according to the compatibility commitments in README.md for the chosen target branch.
• Documentation: Relevant documentation is added or updated.
• Changelog: Significant features, behavior changes, deprecations and fixes are added to CHANGELOG.md.
• Commits: Commit messages follow guidelines in CONTRIBUTING.md, there are no fixup commits left.

[htdvisser]

To make this more useful, maybe we can our tooling parse that API key and write it to a file in .dev or .env or something?

[KrishnaIyer]

@kschiffer / @asmulko : This PR creates an admin API key and writes that to .env/admin_api_key.txt when you run tools/bin/mage dev:initStack.

This means that you can just use this API for CLI commands during automated testing and not have to login on the CLI.