Simplify config storage IPC code

[SvenDowideit]

Ok, so my goal for this was to be able to add a new redux Slice that talks to its counterpart in the main process (in this case to save the values) while having all the code for that interaction only in the 2 files that deal with it.

This will make it easier to make experiments, and add other interactions - as there won't be a need to also add entries to 3 case statements.

I'm not going to deal with the other IPC calls atm, I want to use this to bring back more of the account saving code.

(ignore the file deletions - they're code that was commented out weeks ago, that I fell over as I was redoing this)

[SvenDowideit]

@nathanleclaire and as extra ARGH! when I run npm run lint from the commandline I get no errors. I do see these in the editor, but only if i'm hunting - but there must be a reason :/

and fixing them :)

[SvenDowideit]

ok, merging, I'm going to use PromiseIPC for saving account info, and then we can decide how we feel about it