feat: rewrite public UI component rendering using tunnels (#6117)

feat: rewrite public UI component rendering using tunnels (#6117)

* feat: rewrite public UI component rendering using tunnels

* factor out into components

* comments

* fix variable naming

* fix not hiding welcomeScreen

* factor out AppFooter and memoize components

* remove `UIOptions.welcomeScreen` and render only from host app

* factor out tunnels into own file

* update changelog. Keep `UIOptions.welcomeScreen` as deprecated

* update changelog

* lint

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Co-authored-by: Aakansha Doshi <aakansha1216@gmail.com>