[Java.Base] Update to Microsoft.DotNet.GenAPI 8.0.0-beta.24516.1 (#1272)

Context: https://dev.azure.com/dnceng/public/_artifacts/feed/dotnet-eng/NuGet/Microsoft.DotNet.GenAPI/overview/8.0.0-beta.24516.1

Microsoft.DotNet.GenAPI 8.0.0-beta.24516.1 is the latest 8.0.x
version of Microsoft.DotNet.GenAPI, and as we don't want to require
.NET 9.0 yet, that's the latest version we can use.

Additionally, Microsoft.DotNet.GenAPI 8.0.0-beta.24516.1 does not
contain a `Microsoft.DotNet.GenAPI.dll` which can be used a'la
`dotnet Microsoft.DotNet.GenAPI.dll …`, so migrate to instead use the
MSBuild properties and targets:

  * `$(GenerateReferenceAssemblySource)`=true causes
    Microsoft.DotNet.GenAPI to generate the reference assembly source
    files.

  * `$(GenAPIInputAssembly)`: the assembly to process

  * `$(GenAPILibPath)`: where to resolve `$(GenAPIInputAssembly)`
    assembly references.

  * `$(GenAPITargetPath)`: Where the reference assembly source should
    be written.

Author: jonpryor

Directory.Build.targets

@@ -27,7 +27,7 @@
     <PackageReference Update="Microsoft.Build.Utilities.Core"               Version="17.3.2" />
     <PackageReference Update="Microsoft.CodeAnalysis.CSharp"                Version="4.3.1" />
     <PackageReference Update="Microsoft.CSharp"                             Version="4.7.0" />
-    <PackageReference Update="Microsoft.DotNet.GenAPI"                      Version="7.0.0-beta.22103.1" />
+    <PackageReference Update="Microsoft.DotNet.GenAPI"                      Version="8.0.0-beta.24516.1" />
     <PackageReference Update="Microsoft.NET.Test.Sdk"                       Version="17.5.0-preview-20221003-04" />
     <PackageReference Update="Microsoft.SourceLink.GitHub"                  Version="1.1.1" />
     <PackageReference Update="Microsoft.Xml.SgmlReader"                     Version="1.8.16" />