Pref-based sentry replay, client-specific sentry project support.

[dannon]

WIP, will expand on this, but -- upgrades sentry client, supports secondary client dsn (falling back to single configured project), and enables replay conditionally based on user pref. Might shift that back out of an 'extra' prefs, but I added it there for simplicity for now. Noted a few things for refactoring but I just wanted to get the basic bits working on the client side so we can tinker with this in action.

How to test the changes?

(Select all options that apply)

• I've included appropriate automated tests.
• This is a refactoring of components with existing test coverage.
• Instructions for manual testing are as follows:
  1. [add testing steps and prerequisites here if you didn't write automated tests covering all your changes]

License

• I agree to license these and all my past contributions to the core galaxy codebase under the MIT license.