Group top-level templates

Support grouping templates in the initial screen

# New flow
## First Screen
Choose the codebase you want to generate:

1. Project
2. Add-on
3. Distribution
4. Documentation
5. Devops
6. CI

>2

## Second Screen

1. Frontend add-on
2. Backend add-on
3. Add-on with frontend and backend
4. Seven add-on

> 3

## Third Screen

(Existing flow for the selected template)

