Allow the command line app to roll forward to .NET 9 runtime

Motivation
----------
It's possible for a system running a build to have only the .NET 9 SDK
installed, without the .NET 8 runtime. In this case, setting environment
variables to force a roll forward to .NET 9 is required.

Modifications
-------------
Set the roll forward configuration to Major in the command line app's
runtimeconfig.json.

Results
-------
SDK-style builds will now automatically roll forward to the .NET 9
runtime to run Yardarm if the .NET 8 runtime is unavailable. For best
compatibility, the .NET 8 runtime is still prefered if present.

src/main/Yardarm.CommandLine/Yardarm.CommandLine.csproj

@@ -1,10 +1,18 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
     <TargetFramework>net8.0</TargetFramework>
     <RuntimeIdentifiers>win-x64;linux-x64</RuntimeIdentifiers>
 
+    <!--
+      If .NET 8 isn't installed, allow the command line tool to run on newer frameworks.
+      This may not always work, but provides better compatibility. This option still prefers
+      to use the .NET 8 runtime as specified in TargetFramework above, and only uses a newer
+      runtime if .NET 8 isn't available.
+    -->
+    <RollForward>Major</RollForward>
+
     <!--
       Since we are highly parallelized and doing a lot of SyntaxNode heap allocations, for multicore
       machines we can get fewer GC pauses by using server GC. This is a good default for this project.