Automate Omicron Provisioning Flow

[smklein]

(Context: 7/12 IAM sync discussed this topic)

We've been adding a bunch of features - IdP integration, image generation, gateways + external IPs, IP pools, etc - which are all great features to have - but which requires some manual intervention to set properly within the context of a rack.

For local development, our advice has been "tweak config files, and re-package", or "remember to hit the right endpoints" on setup to make the rack usable. However, in the context of a "real" rack deployment, this isn't really a feasible option. We'd eventually like to:

1. Create a set of packages with configurations that are known to be applicable, regardless of which rack it is deployed to
2. Provide a mechanism - akin to first-time setup via the console - to ensure that all of these known-at-runtime configuration options are set. This could be an interactive program, something which consumes a config file, etc.

This issue tracks providing a program to perform the responsibilities of (2) - either as an interactive part of RSS, as a portion of early boot console setup, or even through a separate config file which we validate, to ensure all these necessary resources have been provided. The end-goal is to make it harder for users to spin up a control plane, and find that some fundamental configuration has not yet been correctly set.