fix: revert shared framework packages to 8.x for net8 Functions host compatibility

The Azure Functions host process runs on net8.0 and loads DurableTask extension
assemblies into its process. Packages like Microsoft.Extensions.*, Bcl.AsyncInterfaces,
and System.Text.Json are part of the .NET shared framework - the host only provides
version 8.0.0.0 of these assemblies.

PR #510 upgraded these to 10.x, which causes FileNotFoundException at runtime:
  Could not load file or assembly 'Microsoft.Extensions.Options, Version=10.0.0.0'

This reverts the 11 shared-framework packages to 8.x while keeping all other
dependency upgrades (Grpc, Protobuf, Azure.Storage.Blobs, Azure.Identity, etc).

Packages reverted:
- Microsoft.Extensions.* (9 packages): 10.0.2 -> 8.x
- Microsoft.Bcl.AsyncInterfaces: 10.0.2 -> 8.0.0
- System.Text.Json: 10.0.2 -> 8.0.5

Test project fix:
- Generators.Tests: VersionOverride for DependencyInjection (net10 test project
  needs 10.x via Functions.Worker transitive dep, safe since tests don't load
  into the Functions host)

global.json: relaxed SDK version to match installed 10.0.104

Author: YunchuWang

Directory.Packages.props

@@ -7,16 +7,22 @@
     <ManagePackageVersionsCentrally>true</ManagePackageVersionsCentrally>
   </PropertyGroup>
 
-  <!-- Microsoft.Extensions.* Packages -->
+  <!-- Microsoft.Extensions.* Packages
+       IMPORTANT: These assemblies are part of the .NET shared framework and load into the
+       Azure Functions host process, which runs on net8.0. Package versions MUST stay at 8.x
+       so the assembly versions (8.0.0.0) match what the host provides. Using 10.x causes
+       FileNotFoundException at runtime because the host cannot satisfy Version=10.0.0.0.
+       DO NOT upgrade to 10.x+ until the Azure Functions host itself targets .NET 10.
+       See: https://github.com/Azure/azure-functions-host (WebJobs.Script.csproj -> net8.0) -->
   <ItemGroup>
-    <PackageVersion Include="Microsoft.Extensions.Caching.Memory" Version="10.0.2" />
-    <PackageVersion Include="Microsoft.Extensions.Configuration.Abstractions" Version="10.0.2" />
+    <PackageVersion Include="Microsoft.Extensions.Caching.Memory" Version="8.0.1" />
+    <PackageVersion Include="Microsoft.Extensions.Configuration.Abstractions" Version="8.0.0" />
     <PackageVersion Include="Microsoft.Extensions.DependencyInjection" Version="10.0.2" />
-    <PackageVersion Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="10.0.2" />
-    <PackageVersion Include="Microsoft.Extensions.Hosting" Version="10.0.2" />
-    <PackageVersion Include="Microsoft.Extensions.Hosting.Abstractions" Version="10.0.2" />
-    <PackageVersion Include="Microsoft.Extensions.Logging.Abstractions" Version="10.0.2" />
-    <PackageVersion Include="Microsoft.Extensions.Options" Version="10.0.2" />
+    <PackageVersion Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="8.0.2" />
+    <PackageVersion Include="Microsoft.Extensions.Hosting" Version="8.0.1" />
+    <PackageVersion Include="Microsoft.Extensions.Hosting.Abstractions" Version="8.0.1" />
+    <PackageVersion Include="Microsoft.Extensions.Logging.Abstractions" Version="8.0.3" />
+    <PackageVersion Include="Microsoft.Extensions.Options" Version="8.0.2" />
     <PackageVersion Include="Microsoft.Extensions.Options.DataAnnotations" Version="10.0.2" />
   </ItemGroup>
 
@@ -82,9 +88,9 @@
     <PackageVersion Include="DotNext" Version="4.13.1" Condition="'$(TargetFramework)' != 'net8.0' AND '$(TargetFramework)' != 'net10.0'" />
     <PackageVersion Include="DotNext" Version="5.19.0" Condition="'$(TargetFramework)' == 'net8.0' OR '$(TargetFramework)' == 'net10.0'" />
     <PackageVersion Include="Microsoft.SourceLink.GitHub" Version="8.0.0" />
-    <PackageVersion Include="Microsoft.Bcl.AsyncInterfaces" Version="10.0.2" />
+    <PackageVersion Include="Microsoft.Bcl.AsyncInterfaces" Version="8.0.0" />
     <PackageVersion Include="System.Linq.Async" Version="6.0.1" />
-    <PackageVersion Include="System.Text.Json" Version="10.0.2" />
+    <PackageVersion Include="System.Text.Json" Version="8.0.6" />
     <PackageVersion Include="System.Collections.Immutable" Version="8.0.0" />
   </ItemGroup>