* app: added desktop app shell based on Electron that runs in the tray, starts a background kopia server and allows access to the UI
* icons: updated icons for the app
* htmlui: flexible containers
This orchestrates building HTMLUI and main binary, only uses built-in shell script and avoids having any dependencies on Unix tools. Latest go and npm are required.
This is enabled by `kopia server --ui` and can be viewed in a browser
at http://localhost:51515/
Right now it can only list snapshots and policies (barely).