Sentry integration for error handling

Using Sentry we want to aggregate errors from production.

Error cases that should be reported:

* Failed symbolication
* File could not be loaded
* UI errors

Requirements:

* Sentry should only aggregate for production builds
* Script should not be included when DNT is enabled

So far I am aware of 3 possible paths to use Sentry:

1. Catching errors in redux: https://github.com/captbaritone/raven-for-redux
1. Catching errors in React:
* https://sentry.prod.mozaws.net/operations/devtools/getting-started/javascript-react/
* https://sentry.io/for/react/
1. Report error like screenshots (concerns with including Raven)
* https://github.com/mozilla-services/screenshots/blob/master/docs/error-handling.md
* https://github.com/mozilla-services/screenshots/blob/master/addon/webextension/background/senderror.js

An issue with Raven that Screenshots mentioned is matching the version of Raven to our instance of Sentry. We might want to consider not using Raven but catching and sending the reports like screenshot does.

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-670)