Update Getting Started guide (#7035)

* start user app edits

* pass through guide

* update assets

* TODOs

* add localepicker back

* lingering preview labels

* markdown tables

* Update docs/tutorials/Developing_a_User_Installable_App.mdx

Co-authored-by: val.le <[email protected]>

* Update docs/quick_start/Getting_Started.mdx

Co-authored-by: val.le <[email protected]>

* Update docs/quick_start/Getting_Started.mdx

Co-authored-by: val.le <[email protected]>

* Update docs/quick_start/Getting_Started.mdx

Co-authored-by: val.le <[email protected]>

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Co-authored-by: val.le <[email protected]>

Author: shaydewael