[BUGFIX beta] Rewrite with transform to use block params

- Rewrites `{{#with foo.bar as bar}}` to `{{#with foo.bar as |bar|}}` instead of `{{#with foo.bar keywordName="bar"}}`.
- Fixes a bug this exposed where `{{#with foo.bar controller="blah" as |bar|}}` was not yielding the object instead of the controller.