Feature/unified solution

[alexhiggins732]

• Add a single solution containing all projects to allow for scanning, dependency management, and analysis of all projects within a single solution.
• Refactors client samples to use a shared Identity Server implementation to eliminate unnecessary code duplication.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 85.47486% with 78 lines in your changes missing coverage. Please review.

Project coverage is 69.68%. Comparing base (0320ceb) to head (5dbf5e5). Report is 1 commits behind head on develop.

Files	Patch %	Lines
...s/Quickstarts/Shared/src/IdentityServer/Program.cs	0.00%	39 Missing :warning:
.../Quickstarts/6_AspNetIdentity/src/Host/SeedData.cs	77.19%	7 Missing and 6 partials :warning:
...entityServer/Quickstart/HttpContextSignInHelper.cs	62.50%	7 Missing and 2 partials :warning:
...ckstarts/5_EntityFramework/src/Host/StartupTest.cs	93.54%	4 Missing and 2 partials :warning:
...spNetIdentity/src/Host/Models/SignManagerHelper.cs	82.35%	2 Missing and 1 partial :warning:
...ickstarts/6_AspNetIdentity/src/Host/StartupTest.cs	95.16%	2 Missing and 1 partial :warning:
...er/Quickstart/Diagnostics/DiagnosticsController.cs	0.00%	0 Missing and 2 partials :warning:
...tityServer/Quickstart/Account/AccountController.cs	83.33%	1 Missing :warning:
.../Shared/src/IdentityServer/Views/Home/Index.cshtml	0.00%	0 Missing and 1 partial :warning:
...ed/src/IdentityServer/Views/Shared/Redirect.cshtml	0.00%	1 Missing :warning:

:exclamation: There is a different number of reports uploaded between BASE (0320ceb) and HEAD (5dbf5e5). Click for more details.

HEAD has 2 uploads less than BASE

| Flag | BASE (0320ceb) | HEAD (5dbf5e5) | |------|------|------| ||3|1|

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #37 +/- ## =========================================== - Coverage 78.87% 69.68% -9.19% =========================================== Files 373 504 +131 Lines 10233 13473 +3240 Branches 1512 1986 +474 =========================================== + Hits 8071 9389 +1318 - Misses 1726 3610 +1884 - Partials 436 474 +38 ```

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