CPLAT-11574: Investigate CLI integration

[greglittlefield-wf]

CPLAT-11574

Providing diagnostics in the IDE is valuable, but there's also value in running those diagnostics in CI to ensure a certain set of changes doesn't introduce bad code.

We need to determine whether we can run the plugin from the command-line using existing tooling:

• dartanalyzer (doesn't work out of the box)
• tuneup
  There may be special flags or something we need to pass to pull in plugins, if the tool doesn't run plugins out of the box.

If we can't, we should research whether the Dart team plans on supporting that.

If it's not supported and won't be for a while, we may want to follow up with work on a custom tool to run these checks via command-line.