Allow acorn rm --ignore-cleanup on services (#1795)

[g-linville]

for #1795

We recently added the --ignore-cleanup flag to acorn rm, which removes some finalizers and ignores the delete event job(s). This was not working for services (and probably wasn't working for nested Acorns either), since the default name validation was blocking names with ., and the logic to find the AppInstance was not checking the public name label. This PR fixes both of those things.

To validate my changes, I am using the following Acornfiles:

// service.Acornfile
containers: "never-ready": {
  image: "nginx:latest"
  probes: readiness: tcp: url: "tcp://localhost:5555"
}

jobs: "fail-on-delete": {
  image: "busybox:latest"
  events: ["create", "delete"]
  entrypoint: ["/script.sh"]
  files: "/script.sh": """
  #!/bin/sh
  echo Starting
  sleep 5
  dne
  """
}

// Acornfile
services: myservice: {
  image: <image built from service.Acornfile>
}

containers: nginx: {
  image: "index.docker.io/nginx:latest"
  ports: ["80/http"]
}

When deploying this app, it is never ready (thanks to the bad container in the service). When you delete the app, it looks like it succeeds in the CLI, but that kicks off the delete job in the service, which fails continuously. Previously, acorn rm --ignore-cleanup <app name>.myservice would fail, but now it works and finishes cleaning everything up.

Checklist

• The title of this PR would make a good line in Acorn's Release Note's Changelog
• The title of this PR ends with a link to the main issue being address in parentheses, like: This is a title (#1216). Here's an example
• All relevant issues are referenced in the PR description. NOTE: don't use GitHub keywords that auto-close issues
• Commits follow contributing guidance
• Automated tests added to cover the changes. If tests couldn't be added, an explanation is provided in the Verification and Testing section
• Changes to user-facing functionality, API, CLI, and upgrade impacts are clearly called out in PR description
• PR has at least two approvals before merging (or a reasonable exception, like it's just a docs change)

[njhale]

Nice!