This commit migrates the `navbar.html` Django template
to handlebars by creating a new file as `navbar.hbs`
within `/static/templates` which is then rendered
using `ui_init` module.
As a part of migration, we also remove the `search_pills_enabled`
and `embedded` parameters from the context attribute as they
are no longer needed now.
Fixes part of #18792.
aryanshridhar