Bug 1074732 - [Messages] Create a mixin to handle the select UI model

- Create a selection mixin and extend the methods into view modules.
- Unify the UI update into one method and adjust the update flow to change the selected data first, then update (visible) UI based on data.
Not sure if the inversion control is a idea pattern here, maybe another intuitive  way that only add listener when inEditMode set true and remove when set to false?