Circular dependency errors and root module errors should not block the rest of tach check

[emdoyle]

Right now, when we build the 'module tree' from the tach.toml configuration, we validate against circular dependencies and the expected root module treatment (if necessary). However, when these checks fail, we immediately return an error and render it in the CLI.

Instead, the tach check command should continue with a full scan for errors even when these validations fail. The validation errors can be displayed in their own segment of the error output.