Reduce the size of the app pages

[severo]

For the components demo, and surely for the other apps like viewers.source.coop and source.coop later.

Route (pages)                              Size     First Load JS
┌ ○ / (788 ms)                             633 B           385 kB
├   /_app                                  0 B             385 kB
├ ○ /404                                   178 B           385 kB
├ ○ /browser (824 ms)                      582 B           385 kB
├ ○ /button (509 ms)                       386 B           385 kB
├ ○ /form (1093 ms)                        973 B           386 kB
├ ○ /viewers (505 ms)                      548 B           385 kB
├ ○ /viewers/loader (850 ms)               648 B           385 kB
├ ○ /viewers/map (614 ms)                  535 B           385 kB
├ ○ /viewers/markdown (662 ms)             470 B           385 kB
├ ○ /viewers/table (857 ms)                471 B           385 kB
└ ○ /viewers/text (486 ms)                 469 B           385 kB
+ First Load JS shared by all              385 kB
  ├ chunks/framework-8a8ee0a30377ce1f.js   45.4 kB
  ├ chunks/main-55d17dc67e4eb6ab.js        33 kB
  ├ chunks/pages/_app-b49219e6605cfaf9.js  305 kB
  ├ chunks/webpack-9cf7fa5af641ace9.js     974 B
  └ css/69cfeb378369c6bc.css               641 B

We could load the required modules (for a specific viewer) on load, not for all the pages.