Fixes: https://github.com/jitsi/jitsi-meet/issues/4049

- Use actions to notify the rest of the app that
  a mic or camera error has occurred
- Use middleware to respond to those notifications
  of errors by showing in-app notifications and
  notifying the external api

Adds a new event fired when Jitsi Meet shows the feedback prompt.

* feat(screenshare): support remote wireless screensharing

- Pass events to the ProxyConnectionService so it can
  handle establishing a peer connection so a remote
  participant, not in the conference, can send a
  video stream to the local participant to use as a
  local desktop stream.
- Modify the existing start screensharing flow to accept
  a desktop stream instead of always trying to create one.

* adjust ProxyConnectionService for lib review changes

Spot will need a way to submit call feedback using the iframe
api. For now expose a method on conference.js to submit that
feedback. Exposing on conference.js looks to be the existing
pattern... Also add an event to notify consumers of the iframe
api that feedback was submitted, as postMessage is async
and the notification can at least give some guarantee maybe.

I haven't updated documentation yet as I'm not confident
about this api.

ESLint 4.8.0 discovers a lot of error related to formatting. While I
tried to fix as many of them as possible, a portion of them actually go
against our coding style. In such a case, I've disabled the indent rule
which effectively leaves it as it was before ESLint 4.8.0.

Additionally, remove jshint because it's becoming a nuisance with its
lack of understanding of ES2015+.

In Chrome M63 a warning is shown, permissions won't be automatically allowed
afterwards. Reference:
https://sites.google.com/a/chromium.org/dev/Home/chromium-security/deprecating-permissions-in-cross-origin-iframes

Setting this early makes us future proof, while working with current versions
too: Chrome < 63 gives an error because it doesn't understand the option and
Firefox seems to ignore it, so both continue to work as before.

In certain scenarios we do need to import files instead of features but
even then it is our coding style to not write the file extension.

We broke external_api.min.js by importing react/features/util which
imported react/features/base/lib-jitsi-meet.

1. To reduce the risks of such a breakage until we add
   external_api.min.js to the torture tests, import as little as
   possible in modules/API/external/external_api.js.
2. Use the global JitsiMeetJS on Web in react/features/base/util.

Web's ExternalAPI accepts an object with properties as one of its
constructor arguments and from which it generated a URL. Mobile's
JitsiMeetView.loadURLObject is supposed to accept pretty much the same
object.

Improves naming.
Fixing typos.
enableLegacyFormat param was working like disableLegacyFormat.
Improves the structure of transport/index.js