Raise if missing settings as soon as app is loaded for specs
See #374
This issue was originally because we call Habitat.raise_if_missing_settings! as the very last thing in the spec_helper.
https://github.com/luckyframework/lucky_cli/blob/b151d4189c1b4ade63b763354edb8e51667b580b/src/web_app_skeleton/spec/spec_helper.cr.ecr#L31-L33
However, when we boot the app locally, we run this right after requiring the app
https://github.com/luckyframework/lucky_cli/blob/b151d4189c1b4ade63b763354edb8e51667b580b/src/web_app_skeleton/src/start_server.cr.ecr#L1-L3
I'm not really sure what benefit we get by moving it up, but it could probably move up 2 lines and still work. Note that the original PR tried to run it right after requiring app, and that failed.