Update to Node 18 without Vite

[loleg]

Update to at least Node 18 in order to permit the upgrade of web3 libraries in #616 and #410

Is it possible to stay with our current build system? Has there been a new approach since last year in the community? (Surely we are not the only project struggling with this migration) Could we do something more simple or automated to update the frontend?

We have hit a bottleneck in our attempts to upgrade the frontend to more modern versions of Node, Vue and - critically - the build system Vite. The partial work on this can be found in #452