make "dart format" check non-scoring check

[jonasfj]

When/if the default line width for dart format becomes configurable, as being discussed in https://github.com/dart-lang/dart_style/issues/833, we should do the following:

• Stop granting point for code being formatted with "dart format".
• Make a suggestion when code is not formatted with "dart format" (but not points deducted).
• Increase point for up-to-date dependencies from 10 to 20 points. (Ensuring overall points remain the same).

Reasoning: Code formatting does not imply quality. But we do want to make people aware that formatting is a thing, if they haven't otherwise discovered it.

[Levi-Lesches]

I don't know if the feature is widely available yet, but that issue has been closed ^

[sigurdm]

I think we'll close this, as the most widespread complaint against the formatter (configurable line-widths) has been solved.