This commit removes the ability to enable/disable the Sidebar on a per
user basis and introduces a site wide setting. For testing purposes, sidebar can be enabled/disabled via the `enable_sidebar=1` or `enable_sidebar=0` query param.
When the experimental Sidebar is enabled, the hamburger drop down is replaced by a sidebar drop down. A user is given the ability to dock and undock the sidebar depending on their personal preference.
Do also note that the experimental sidebar is well, considered experimental at this point so I do not intend for the features here to be perfect. What I aim to do here is to ship the changes fast so that it can be used internally by the team to provide feedback. Custom links added by plugins and dark mode toggle has not been implemented as part of this commit as I aim to tackle it in another commit.
Co-authored-by: awesomerobot <kris.aubuchon@discourse.org>
