feat(quasar-cli): Add MPA support

quasar-cli/.eslintrc.js

quasar-cli/.gitignore

quasar-cli/apps/quasar-classic-django-example/html_files.js

quasar-cli/apps/quasar-classic-django-example/pages.js

...i/apps/quasar-classic-django-example/pages/main/final.pug

...ps/quasar-classic-django-example/pages/main/html_files.js

...pps/quasar-classic-django-example/pages/main/main_page.js

...li/apps/quasar-classic-django-example/pages/main/page.pug

...ar-cli/apps/quasar-classic-django-example/shared/index.js

...pps/quasar-classic-django-example/shared/layout/layout.js

...ps/quasar-classic-django-example/shared/layout/layout.pug

...pps/quasar-classic-django-example/shared/quasar/quasar.js

quasar-cli/apps/shared/webpack-html-templates/index.html

quasar-cli/apps/shared/webpack-html-templates/index.pug

quasar-cli/package-lock.json

quasar-cli/package.json

quasar-cli/params.js.example

quasar-cli/quasar.conf.js

quasar-cli/src-pwa/custom-service-worker.js

quasar-cli/src-pwa/register-service-worker.js