Upgrade frontend JS components

[knadh]

Ref: #339

Frontend deps node-sass and sass-loader fail to build on Node 16. It appears that upgrading these libs to run on Node 16 require Buefy (UI lib) and Vue to be upgraded. There are breaking syntactic and functional changes in the latest version of Buefy that require changes to all <b-table> implementations, of which there are many in the app. This is primarily to do with Vue 2.6's new v-slot directive.

Also, the latest version of Buefy does not seem to require any sass libs at all for customizing CSS, so it might be possible to eliminate these dependencies entirely. It's also interesting to note that the latest version of sass-loader (which does not work on Node 16) in turn recommends using dart-sass over node-sass.

Until these issues are resolved and the frontend is upgraded cleanly, it is recommended to continue using Node 14 to compile the frontend.

PS: Yet another day in the Node/JS "ecosystem" ;(

[knadh]

#371 closes this.