Contribute sidebar/panel views that Joyriders can populate

[PEZ]

Contributing a view to VS Code's sidebar is one of those static things. See: https://code.visualstudio.com/api/references/contribution-points#contributes.views

Currently there is no way (I think) for a Joyride script to populate the sidebar. We could contribute this from Joyride and provide some API for populating it.