Add ability to use WebWorkerRpcDriver on vite and nextjs examples

[cmdcolin]

Currently our vite/nextjs examples are not enabled to do web worker rpc. It may be valuable to create examples of this but there are hurdles to each

For nextjs, the component tries to get rendered server side, and it gets confused by importing directly from '@jbrowse/react-linear-genome-view/esm/makeWorkerInstance' (which has esm export statement, which the server side does not like, it prefers the commonjs)

For vite, it gives a lot of odd errors related to MIME type. I found that adding the filename extension could help with this. Alternative code

At least for vite dev mode, haven't tried production, can get closer to working with this

const state = createViewState({
      assembly,
      tracks,
      makeWorkerInstance: function makeWorkerInstance() {
        return new Worker(
          new URL(
            "@jbrowse/react-linear-genome-view/esm/rpcWorker.js", // actual rpcWorker with file extension, has proper mime type
            import.meta.url
          ),
          { type: "module" } // needed since it uses import
        );
      },
      defaultSession,
      configuration: {
        rpc: {
          defaultDriver: "WebWorkerRpcDriver",
        },
      },
    });

[cmdcolin]

note that the above still goes into an infinite loading state on the tracks and maybe throws (err insufficiet resources? it loads a lot of js to the client...)

[cmdcolin]

possibly the vanillajs example too if possible

[cmdcolin]

this has now been deployed across the embedded demos for both app (nextjs and vite) and lgv (nextjs and vite) demos