Auth engine rework

[sungam3r]

This PR adds many new classes and interfaces to unify authorization architecture with such from the server project. Also adds APIs from https://github.com/graphql-dotnet/server/pull/480 to build custom errors and messages.

Many classes are similar to those from ASP.NET Core (but not all). Of course, the project still does not have any dependencies from ASP.NET Core bits.

fixes #127 fixes #121

[Shane32]

I'll need a little time to look at it. Hopefully I can do so tonight.

[codecov-io]

Codecov Report

Merging #128 (51de6ed) into master (46eaa4c) will increase coverage by 12.28%. The diff coverage is 90.43%.

@@             Coverage Diff             @@
##           master     #128       +/-   ##
===========================================
+ Coverage   80.84%   93.12%   +12.28%     
===========================================
  Files          10       17        +7     
  Lines         214      291       +77     
  Branches       32       42       +10     
===========================================
+ Hits          173      271       +98     
+ Misses         32       13       -19     
+ Partials        9        7        -2     

Impacted Files	Coverage Δ
...raphQL.Authorization/AuthorizationPolicyBuilder.cs	100.00% <ø> (+54.54%)	:arrow_up:
src/GraphQL.Authorization/AuthorizationError.cs	62.50% <62.50%> (ø)
...ation/Requirements/AuthenticatedUserRequirement.cs	85.71% <66.66%> (+10.71%)	:arrow_up:
...ion/Requirements/ClaimsAuthorizationRequirement.cs	86.53% <86.53%> (ø)
...aphQL.Authorization/AuthorizationValidationRule.cs	91.50% <87.83%> (-4.86%)	:arrow_down:
src/GraphQL.Authorization/AuthorizationFailure.cs	100.00% <100.00%> (ø)
src/GraphQL.Authorization/AuthorizationPolicy.cs	100.00% <100.00%> (+14.28%)	:arrow_up:
...horization/AuthorizationPolicyBuilderExtensions.cs	100.00% <100.00%> (ø)
src/GraphQL.Authorization/AuthorizationResult.cs	100.00% <100.00%> (ø)
src/GraphQL.Authorization/AuthorizationSettings.cs	100.00% <100.00%> (+66.66%)	:arrow_up:
... and 19 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 46eaa4c...51de6ed. Read the comment docs.