[Dashboard] Re-Brand / VS Code Information Page for Existing Users

[svenefftinge]

With the next release, we will land a major redesign/rebranding of Gitpod.
We want to tell existing users when they land on gitpod.io for the first time about the changes and how excited we are.
The page should suggest to go with VS Code as the default IDE but give users the possibility to dismiss, so they keep using Theia.

Questions

1. Do we want to mention the Custom IDE functionality here?
2. Should we rename the primary action button from Opt-in and Continue to Switch to VS Code as the new dashboard won't be an opt-in?

Designs

Loading	Loading (Spacing)

Dashboard	Dashboard (Spacing)

See also design specs.

[svenefftinge]

@gtsiolis we'd need a screen for existing users, suggesting them to opt-in using VS Code.