Outbound live stream notifications (#1663)

* First pass at browser, discord, twilio notifications

* Commit updated Javascript packages

* Remove twilio notification support

* Email notifications/smtp support

* Fix Firefox notification support, remove chrome checks

* WIP more email work

* Add support for twitter notifications

* Add stream title to discord and twitter notifications

* Update notification registration modal

* Fix hide/show email section

* Commit updated API documentation

* Commit updated Javascript packages

* Fix post-rebase missing var

* Remove unused var

* Handle unsubscribe errors for browser push

* Standardize email config prop names

* Allow overriding go live email template

* Some notifications cleanup

* Commit updated Javascript packages

* Remove email/smtp/mailjet support

* Remove more references to email notifications

Co-authored-by: Owncast <owncast@owncast.online>

webroot/img/notification-bell.svg

@@ -0,0 +1,3 @@
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+</svg>