Create a VSCode Headlamp plugin

[joaquimrocha]

VSCode is widely used and we want to leverage that in order to make it easier to onboard developers (especially new ones) to Headlamp. Therefore, we should have a plugin for VSCode, called Headlamp, with the following capabilities:

• [x] Provide options for creating a new Headlamp plugin
• [x] Run Headlamp from an existing clone (and offer to clone it if it doesn't exist)

Optional:

• [ ] Install Headlamp in-cluster (using kubectl)

[illume]

There's a preview release inside vscode.

• https://github.com/headlamp-k8s/vscode-extension-headlamp
• https://marketplace.visualstudio.com/items?itemName=headlamp.headlamp&ssr=false#overview

[illume]

@joaquimrocha I addressed the issues from the vscode extension review the other day.

• [x] Show instructions for how to use it.
  • [x] make screenshot for readme
• [x] remove debug message on "Create new plugin", shows "hello" message
• [x] check if headlamp is in home folder, not just vscode workspace.
• [x] bug when no workspace files
  • [x] show a message "You have not yet opened a folder"

Here:

• https://github.com/headlamp-k8s/vscode-extension-headlamp
• https://marketplace.visualstudio.com/items?itemName=headlamp.headlamp&ssr=false#overview