SF-3686 Enable SignalR reconnecting with statefulness

[pmachapman]

This PR helps the SignalR server and client to reconnect and resend any missed messages if the connection is interrupted for some reason, such as connectivity issues.

I have also cherrypicked a commit from #3638 that will unsubscribed from notifications, to ensure that the server does not remember messages for clients that no longer require SignalR notifications for a sync or draft.

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This change is 

[codecov]

Codecov Report

❌ Patch coverage is 40.00000% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.90%. Comparing base (f5e9bcc) to head (4a3f116).
⚠️ Report is 1 commits behind head on master.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/SIL.XForge.Scripture/Startup.cs	0.00%	4 Missing ⚠️
...ntApp/src/app/core/project-notification.service.ts	0.00%	3 Missing ⚠️
.../app/sync/sync-progress/sync-progress.component.ts	75.00%	1 Missing ⚠️
...draft-history-list/draft-history-list.component.ts	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3655      +/-   ##
==========================================
- Coverage   81.91%   81.90%   -0.01%     
==========================================
  Files         618      618              
  Lines       38542    38551       +9     
  Branches     6285     6309      +24     
==========================================
+ Hits        31570    31574       +4     
+ Misses       6012     6004       -8     
- Partials      960      973      +13     

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[RaymondLuong3]

@RaymondLuong3 reviewed 4 files and all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @pmachapman).

[RaymondLuong3]

Let's get this to QA and see if it makes a difference. I have seen drafts on QA that complete but a page refresh is needed to see the new draft.

@RaymondLuong3 made 1 comment.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @pmachapman).