[wasm] Fix debugger tests run on Windows (#79124)

This broke recently:

```
  'C:\Program' is not recognized as an internal or external command,
  operable program or batch file.
D:\a\_work\1\s\src\mono\wasm\debugger\DebuggerTestSuite\DebuggerTestSuite.csproj(57,5): error MSB3073: The command "C:\Program Files\dotnet\dotnet.exe test --no-build -s D:\a\_work\1\s\artifacts\bin\DebuggerTestSuite\x64\Debug\.runsettings -t --nologo -v:q" exited with code 9009.
```

- this is breaking because we are running `src/mono/wasm/debugger/DebuggerTestSuite/DebuggerTestSuite.csproj`
    `<Exec Command="$(DotNetTool) test ..." />`

  - and `DotNetTool` here is `c:\Program Files\dotnet\dotnet.exe`, and
    the shell command breaks because of the space.
  - this broke because recently we moved to building with `7.0.100`. And
    when the version used for building matches the version installed on
    the system, the system dotnet is used.
    - but when it doesn't, it gets installed in
      `</repo/checkout>/.dotnet/dotnet`
    - So, because of the recent update the path changed to `C:\Program files`,
      and broke the command.
    - The fix is to simply quote the path.

src/mono/wasm/debugger/DebuggerTestSuite/DebuggerTestSuite.csproj

@@ -54,7 +54,7 @@
           BeforeTargets="CopyTestZipForHelix"
           DependsOnTargets="_GenerateRunSettingsFile">
 
-    <Exec Command="$(DotNetTool) test --no-build -s $(RunSettingsFilePath) -t --nologo -v:q" ConsoleToMSBuild="true">
+    <Exec Command="&quot;$(DotNetTool)&quot; test --no-build -s $(RunSettingsFilePath) -t --nologo -v:q" ConsoleToMSBuild="true">
       <Output TaskParameter="ConsoleOutput" ItemName="_ListOfTestsLines" />
     </Exec>