Add Support for SDK Style csproj

[SkyeHoefling]

The csproj uses the legacy style csproj and we should update it to use the new SDK Style csproj. This introduces some difficulties with the build tasks if I remember correctly. Here is an example of what I am thinking as a starting point

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net472</TargetFramework>

    <!-- This allows VS Code Debugging -->
    <DebugType>Portable</DebugType>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="DotNetNuke.Abstractions" Version="9.4.2" />
    <PackageReference Include="DotNetNuke.DependencyInjection" Version="9.4.2" />
    <PackageReference Include="DotNetNuke.WebApi" Version="9.4.2" />
  </ItemGroup>

  <ItemGroup>
    <Reference Include="System.Web" />
  </ItemGroup>

</Project>

[david-poindexter]

@ahoefling I thought about this, but as you said, this may have some negative ramifications regarding the MSBuild hooks. We should investigate nonetheless. Thanks for posting the issue!