Expandable and Collapsible Sidebars UI

[jolanglinais]

Is your feature request related to a problem? Please describe.
Adapt the current functionality of hiding the sidebars to use an arrow component

Describe the solution you'd like
Expand button default and hover
https://projects.invisionapp.com/d/main#/console/16741009/370418065/preview

Cursor hovered on pane revealing a subtle border and the collapse button, which is otherwise not visible.
https://projects.invisionapp.com/d/main#/console/16741009/380412036/preview

Cursor hovered over collapse button
https://projects.invisionapp.com/d/main#/console/16741009/380412037/preview

Describe alternatives you've considered
N/A

Additional context
N/A

[Michael-Grover]

@irmerk Is there a way I can have edit access for this description? I just want to update the images to these:

[jolanglinais]

@Michael-Grover unsure if I can do that, but I updated the images so you can remove them from this comment.

[jolanglinais]

Start with #170, #115, and #142