Add ObjectPath to AspNetItemValueLayoutRenderer

[bakgerman]

Changed as little code as possible, added 2 new unit tests

[codecov-commenter]

Codecov Report

Base: 70% // Head: 69% // Decreases project coverage by -1% ⚠️

Coverage data is based on head (7bf39f0) compared to base (0176c44).
Patch coverage: 67% of modified lines in pull request are covered.

Additional details and impacted files

@@          Coverage Diff          @@
##           master   #890   +/-   ##
=====================================
- Coverage      70%    69%   -1%     
=====================================
  Files          65     65           
  Lines        1218   1245   +27     
  Branches      308    323   +15     
=====================================
+ Hits          850    861   +11     
- Misses        229    237    +8     
- Partials      139    147    +8     

Impacted Files	Coverage Δ
src/Shared/Internal/PropertyReader.cs	56% <50%> (-13%)	⬇️
...d/LayoutRenderers/AspNetItemValueLayoutRenderer.cs	94% <100%> (+1%)	⬆️
.../Shared/LayoutRenderers/AspNetMvcActionRenderer.cs	67% <0%> (-13%)	⬇️
...red/LayoutRenderers/AspNetMvcControllerRenderer.cs	67% <0%> (-13%)	⬇️
...tRenderers/AspNetRequestRouteParametersRenderer.cs	17% <0%> (+7%)	⬆️

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[snakefoot]

Thank you for making the pull-request. The objectpath for ${event-properties} works like this:

public class Person
{
    public string FirstName { get; set; }
}

logger.Info("Hello {Customer}",  new Person { FirstName = "Bob" });

Where you can lookup the FirstName-property like this ${event-properties:item=Customer:objectpath=FirstName} (Outputs: "Bob")

So AspNetItemValueLayoutRenderer.Item-property should remain a [RequiredParameter] (Since Item and ObjectPath should be working together)

[bakgerman]

Altered the code to match the comment above.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

90.0% Coverage
0.0% Duplication

[snakefoot]

Thank you again for another fine contribution.

[snakefoot]

Updated wiki:

https://github.com/NLog/NLog/wiki/AspNetItem-layout-renderer
https://github.com/NLog/NLog/wiki/AspNet-HttpContext-Item-Layout-Renderer
https://github.com/NLog/NLog/wiki/AspNetSession-Layout-Renderer