feat: fixed class vs className incorrect use

[Markkos89]

class prop bad use fix

• fixed class vs className props incorrect use in the nextjs templates's files

• changed class to className prop in:

  • templates/frontend/next-app/src/app/hello-components/page.js
  • templates/frontend/next-page/src/pages/hello-components/index.js
  • templates/frontend/vanilla/src/components.js files

Note: Sorry for the double quotes it's my lint doing some messy trick I will try to fix it