Implement frontend using Rum about dannet

[simongray]

Current status as of 0a53583 (tracked in feature/22-frontend) is that the components are in the process of being refactored. This work is quite significant since the original code was basically all about delivering an MVP before running out of time in the DanNet project for the year 2021.

Once this initial refactoring process is over, shadow-cljs needs to be set up with reitit in the frontend taking care of frontend routing. These routes will need to be carefully integrated with the backend routes to ensure that we end up with a smooth progressive app experience, without routes getting caught in between the two. All routes reachable by a web browser should always be present in both.

Finally, work on frontend-specific endpoints can commence. An endpoint will need to be able to deliver a partial entity and another endpoint will need to be able to deliver triples based on a single [?s ?p ?o] pattern where the ?s and ?p are known in advance.

[simongray]

Current status as of a33726b is that basic hydration is working, but LangStrings aren't being properly encoded/decoded during the transit. I think I will need to implement two basic handler functions to fix this.

Other than that things are going well.