Fetch DHE js api from server

[bmingles]

We need to fetch the DHE JS api from a running server.

• DHE: split out npm packages containing necessary types
  • DH-17425: web-client-ui minimal monorepo
  • DH-16725: @deephaven-enterprise/jsapi-types is related but not strictly necessary for this task).
• Seems likely all runtime code should come from the server while types will need to be installed from a package to facilitate dev of the vscode extension. aka. types aren't needed for runtime.
• Replace internal require-jsapi npm package with an external one #155 (dependent on ehttps://github.com/jsapi - improvements for 3rd party consumers deephaven-core#5537)