Swap TFM order

- Start with the newest to see if that fixes Stryker.
- Explicitly target Debug for mutation tests.
- Add missing `eng` items to the Solution Items.

Polly.sln

@@ -29,9 +29,14 @@ EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "eng", "eng", "{04E3C7C5-31F7-4CD6-8BEC-C1032527D231}"
 	ProjectSection(SolutionItems) = preProject
 		eng\Analyzers.targets = eng\Analyzers.targets
+		eng\Benchmark.targets = eng\Benchmark.targets
+		eng\bump-version.ps1 = eng\bump-version.ps1
 		eng\Common.targets = eng\Common.targets
 		eng\Library.targets = eng\Library.targets
+		eng\stryker-config.json = eng\stryker-config.json
 		eng\Test.targets = eng\Test.targets
+		eng\update-baselines.ps1 = eng\update-baselines.ps1
+		eng\update-changelog.ps1 = eng\update-changelog.ps1
 	EndProjectSection
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Polly.Core.Benchmarks", "bench\Polly.Core.Benchmarks\Polly.Core.Benchmarks.csproj", "{CC306C35-E3BC-4F0B-AB8C-B9D4C82DC3DE}"

eng/stryker-config.json

@@ -18,6 +18,7 @@
       "block",
       "statement"
     ],
+    "configuration": "Debug",
     "target-framework": "net8.0",
     "thresholds": {
       "high": 100,

test/Polly.Specs/Polly.Specs.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0</TargetFrameworks>
     <TargetFrameworks Condition="$([MSBuild]::IsOSPlatform('Windows'))">$(TargetFrameworks);net481</TargetFrameworks>
     <Nullable>enable</Nullable>
     <ProjectType>Test</ProjectType>