[IMP] web: new navbar in community

The navbar in community now looks more like the navbar in enterprise.

Here is a sum-up of the changes in community:

- The navbar in community is now in blue, instead of black.
- No more app list that almost fills the whole navbar: there is
  now an "Apps Menu" in the left-most side of the navbar.
- No more sidebar for the menus inside an app: those menus are
  now located in the middle part of the navbar.

The navbar in community does not support mobile (< 768px width),
but it should still somewhat usable on most mobile devices.
As for the website navbar, it has been unchanged and should still
support mobile layout.

Task-ID 1878649