Signed-off-by: Tao Wang <twang2218@gmail.com>

Closes #20918

Closes #13991

Main idea is to keep left sidebar static so user is not confused by
changing context. Instead we put changing navigation with changing
content in one main block

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

This fixes the authorized applications not being revoked properly at
`/profile/applications`.

Fixes #14370.

Closes #14509

Previously we were doing all of kinds of code gymnastics and flash abuse
in order to work with a Doorkeeper controller but have it _appear_ at
the `/profile/applications` path. Fortunately we can just tell Rails to
use a different controller to handle that route, and we get the best of
both worlds.