EPIC: Jetty follow-up tracking issue

[niloc132]

The existing server-jetty (as part of #1731) is focused primarily on making local development easier (no need to involve docker), as well as some ideas of simplifying local deployments (again, no need to involve docker, plus local filesystem access, local python venvs, etc).

There are two main shortcomings over the netty+docker setup.

• WebDAV support, for notebooks. Arguably, this feature should be rewritten to be more secure, at least to require authentication before allowing write access. There are servlet implementations for webdav, but they aren't compatible with the latest servlet apis - they can probably be mechanically updated as a build step, but it may be easier to just switch to a gRPC api instead.
• SSL support, for production deployments and to use http2 from the browser. Two aspects need to be set up here:
  • First, a grpc-web implementation needs to exist for servlets (this is the remaining component of EPIC: Evaluate Jetty as replacement for Netty #1270), which mostly means meeting in the middle between the new grpc-servlet project and the websocket implementation.
  • Second, Jetty's ssl connector needs to be configurable, from config files, command line, etc.

[niloc132]

SSL support is completed. WebDAV support is not planned, this is covered by the StorageService.