Add official VS Code extension

[jonah-iden]

First version of the open collaboratio vscode extension.

Contains the ability to Share Text editor state and the hosts file system

How to test

• build the extension with vsce package --no-dependencies
• install via vsix into Vscode
• start the open-collaboration-server (easiest is through the debug configuration)
• open multiple windows and open a workspace in the host window
• on the status bar you can find a OCT item. Clicking it should reveal the option to create or join a room