Transplant UI code into an RSpack project.

[sleepycat]

The ui service is based a scaffold generated by Create React App (CRA). CRA has a pretty uncertain future at this point, and includes a lot of stuff that better options exist for. Case in point: CRA includes Webpack. Though awesome, it's frustratingly slow and this has caused folks to go and rewrite it in Rust... the result is RSpack.
Their quickstart generates a something similar to CRA, but much simpler and with much better performance.
Transplanting our code/components into their scaffold would be a nice win on a number of fronts.

@Collinbrown95 created a working integration of the Lingui i18n library with the Rspack quickstart for this purpose.