Pinned sidebar navigation option

## What does this MR do?

Gives the ability to pin the sidebar navigation. Pinning is only possible on screens with above `lg` which is `1200px` if not it reverts to being hidden by default.

## What are the relevant issue numbers?

Closes #18542 

## Screenshots (if relevant)

### Un-pinned

![Screen_Shot_2016-06-15_at_17.29.08](/uploads/82b7495df6ea46a2334a7c25d03b019b/Screen_Shot_2016-06-15_at_17.29.08.png)

### Pinned

![Screen_Shot_2016-06-15_at_17.29.41](/uploads/3eb381be807985d0a9583f000cb802f9/Screen_Shot_2016-06-15_at_17.29.41.png)

See merge request !4683