Bug 1074622 - [Stingray] Scaffold the TV browser

* Clone apps/browser to tv_apps/browser.
Bug 1074622 - [Stingray] Scaffold the TV browser

* Restructure HTML structure and style for TV browser UI.
* Draft modules for TV browser.
* add tv_apps/browser in build/config/tv/apps-engineering.list
Merge pull request #25319 from begeeben/1074622_scaffold_the_tv_browser

Bug 1074622 - [Stingray] Scaffold the TV browser, r=:timdream, :rexboy, :evelyn