Bundle sizes are unchanged but now we no longer pull in the
Electron-specific FS code on the web version

- Fix socket connection issues when reloading
- Fix external url clicking & middle clicking internal links
- Remove broken menu option. Easier for now than refactoring the
settings panel it now lives in. We can add it back later if needed?

Updates to the latest version of electron and moves the backend-frontend
communication from node-ipc to websockets. This resolves the previous
roadblock regarding `nodeIntegration` .

Done

- Remove node-ipc in favour of websockets. 
- Move file copying out of `preload.js` to avoid importing module `fs`
there
- Bump all electron pacakge versions to the latest
- Added new package for finding open ports as node-ipc is gone
- Tweaked webpack config for above changes


Partially fixes #468

Questions/ Pending:
- Literally every single test fails for me, presumably some issue with
my setup/environment.
- The websocket communication is not using TLS. I'm not sure how to
enable this, or if we even need to as its all local.
- Still need to create the CI for building/deploying but I'm not sure
where start in this regard as i have no exp with it. Presumably we will
need to point the electron auto-updater to the github releases url's. If
people are happy with this PR I will look at adding the CI before its
merged.
- In dev mode only, I have disabled TLS security becuase my docker
container's cert is not signed. I _assume_ this will be true for other
people who spin up the server on thier own hardware. Perhaps I just need
to change my cert to one from letsencrypt or something...

Notes.
I have not touched javascript in eons so my apologies if the commit
trail is a bit fragmented. I tried to keep them fairly contained and
then there is a slightly gnarly final commit fixing all the linter
issues... Please let me know if you want me to squash some commits etc.

I initially tried to move this to web workers the same way the web app
does it but this was unsuccessful. I have found no way to spin up a
worker in one place (frontend/backend) and then pass this worker to the
other. The electron ipc channels don't allow you to directly pass
objects such as workers, everything is cloned/serialised. Passing a port
number so the other end can spin up its own socket works fine.

---------

Co-authored-by: Shazib Hussain <contact@shazib.com>
Co-authored-by: Jed Fox <git@jedfox.com>

Switch to TS version of `no-unused-vars` rule. 

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