Require class property type annotation

A big thank you for this great project.

I'm looking a rule for that would require type annotation for class property. For instance:

```js
class Foo {
// throws an error because bar is missing a type annotation.
bar;
}
```

Does this rule exists already and I missed it from the documentation maybe?

Start by reviewing the existing rule documentation and related rules in the ESLint plugin to find the appropriate entry point and test conventions. The work is done when class properties without type annotations are reported while annotated properties are accepted, with the rule documented and covered by tests.

Written by the indexing model from the issue text.