[6.5] Story: Update Scaffold Template

[adriancofie]

Description

Update cgov-react-app-playground scaffold template to use shared library by default.

Parent Issue: #EPIC_6

Sub-Tasks

• Add @nciocpl/react-app-shared to template dependencies
• Update example code to use shared components
• Remove duplicate atomic component folder
• Update scaffold documentation

Notes

• New apps should use shared library from the start