refs https://github.com/TryGhost/Team/issues/450
Initial prototype of new launch-site wizard, meant to speed up the setup of a members site with the following steps:
1. Customise design
2. Connect Stripe
3. Set subscription pricing
- added wizard link to dashboard screen
- added `/launch/*` screens representing the wizard steps
- duplicated and refactored relevant general and members setting code and templates into each step
refs https://github.com/TryGhost/Team/issues/450
- duplicated and refactored/updated members pricing settings UI from labs to the "set pricing" step of the launch site wizard
refs https://github.com/TryGhost/Team/issues/450
- duplicated and refactored/updated direct and connect settings UI from labs to the "connect stripe" step of the launch site wizard
- updated wizard buttons to be right-aligned
refs https://github.com/TryGhost/Team/issues/450
- moved next/finish buttons into wizard step components in case they need to save before triggering transition
- added icon, logo, and cover image upload+removal to "customise design" step alongside a preview that reloads each time an image is changed
refs https://github.com/TryGhost/Team/issues/450
- adds `launch/*` routes corresponding to launch wizard steps
- sets up navigation between each wizard step
- adds components for each `launch/*` step to contain step-related functionality and facilitate later refactoring to a generalised wizard component
- adds link to the launch wizard from the dashboard screen
