Support authenticating proxies

[CharlieHess]

Electron's net module supports authenticating proxies out of the box, however, we need to listen to an additional event and invoke a callback, otherwise the proxied request becomes a black-holed request.

This is pretty rudimentary but we'll just check the options passed to the request for user and password fields. If those fields aren't provided we'll abort the request and bubble up an error.

[CharlieHess]

cc @arantes555 we're using electron-fetch in Slack and this fixes a big issue. Mind taking a look?

[arantes555]

@CharlieHess Thanks for the PR ! Glad to see electron-fetch being used ;) I have no trouble with your PR, and spent a bit of time earlier today cleaning up and updating master so the tests pass. However, I wanted to write a few tests for your feature before merging it. I've started in the https://github.com/arantes555/electron-fetch/tree/proxy-auth-test branch, if you wanna take a look. I'll merge and publish a new version as soon as I got them running :)

[CharlieHess]

@arantes555 awesome, definitely admire the test coverage here. ✨

[codecov]

Codecov Report

Merging #1 into master will decrease coverage by 0.98%.
The diff coverage is 33.33%.

@@            Coverage Diff             @@
##           master       #1      +/-   ##
==========================================
- Coverage   99.74%   98.76%   -0.99%     
==========================================
  Files           6        6              
  Lines         399      405       +6     
  Branches      131      133       +2     
==========================================
+ Hits          398      400       +2     
- Misses          1        5       +4

Impacted Files	Coverage Δ
src/index.js	93.97% <33.33%> (-4.73%)	⬇️
src/fetch-error.js	100% <0%> (ø)	⬆️

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[tex0l]

Hey @CharlieHess I adjusted a few things and merged your PR in the test branch https://github.com/arantes555/electron-fetch/tree/proxy-auth-test @arantes555 created.
It turns out that writing those tests pointed out a bug: the session argument was being ignored and replaced by electron.session.fromPartition('electron-fetch'), so that the ses.setProxy didn't do much when testing authenticated and unauthenticated proxies...

It is now solved, and the tests pass.

@arantes555 could you review my commits and publish if it's ok for you ?

[arantes555]

Did a tiny bit of cleanup and merged :) publication coming in a few minutes

[arantes555]

@CharlieHess v1.1.0 is published :) Thanks ! I'd love to hear more about how you're using it at Slack ;)

[CharlieHess]

@arantes555 thanks for the quick turnaround!

Newer versions of Slack (from 3.0 on) will unload some "tabs" / teams based on usage. Those unloaded tabs will still make API calls to Slack from the Node.js process, so we can show notifications / badges. And all those API calls from the main process will use electron-fetch. 😁