[PM-16787] Web push enablement for server (#5395)

* Allow for binning of comb IDs by date and value

* Introduce notification hub pool

* Replace device type sharding with comb + range sharding

* Fix proxy interface

* Use enumerable services for multiServiceNotificationHub

* Fix push interface usage

* Fix push notification service dependencies

* Fix push notification keys

* Fixup documentation

* Remove deprecated settings

* Fix tests

* PascalCase method names

* Remove unused request model properties

* Remove unused setting

* Improve DateFromComb precision

* Prefer readonly service enumerable

* Pascal case template holes

* Name TryParse methods TryParse

* Apply suggestions from code review

Co-authored-by: Justin Baur <19896123+justindbaur@users.noreply.github.com>

* Include preferred push technology in config response

SignalR will be the fallback, but clients should attempt web push first if offered and available to the client.

* Register web push devices

* Working signing and content encrypting

* update to RFC-8291 and RFC-8188

* Notification hub is now working, no need to create our own

* Fix body

* Flip Success Check

* use nifty json attribute

* Remove vapid private key

This is only needed to encrypt data for transmission along webpush -- it's handled by NotificationHub for us

* Add web push feature flag to control config response

* Update src/Core/NotificationHub/NotificationHubConnection.cs

Co-authored-by: Justin Baur <19896123+justindbaur@users.noreply.github.com>

* Update src/Core/NotificationHub/NotificationHubConnection.cs

Co-authored-by: Justin Baur <19896123+justindbaur@users.noreply.github.com>

* fixup! Update src/Core/NotificationHub/NotificationHubConnection.cs

* Move to platform ownership

* Remove debugging extension

* Remove unused dependencies

* Set json content directly

* Name web push registration data

* Fix FCM type typo

* Determine specific feature flag from set of flags

* Fixup merged tests

* Fixup tests

* Code quality suggestions

* Fix merged tests

* Fix test

---------

Co-authored-by: Justin Baur <19896123+justindbaur@users.noreply.github.com>

src/Core/Constants.cs

@@ -172,6 +172,7 @@ public static class FeatureFlagKeys
     public const string AndroidMutualTls = "mutual-tls";
     public const string RecoveryCodeLogin = "pm-17128-recovery-code-login";
     public const string PM3503_MobileAnonAddySelfHostAlias = "anon-addy-self-host-alias";
+    public const string WebPush = "web-push";
     public const string AndroidImportLoginsFlow = "import-logins-flow";
     public const string PM12276Breadcrumbing = "pm-12276-breadcrumbing-for-business-features";