Check if we are running under dotnet.exe

When targeting a netcoreapp without a specified runtime, we need to use
`dotnet.exe [dll]` to run the application.

src/Topshelf/Runtime/Windows/HostServiceInstaller.cs

@@ -153,16 +153,19 @@ static TransactedInstaller CreateTransactedInstaller(Installer installer)
 
             Assembly assembly = Assembly.GetEntryAssembly();
 
+            Process currentProcess = Process.GetCurrentProcess();
+
             if (assembly == null)
                 throw new TopshelfException("Assembly.GetEntryAssembly() is null for some reason.");
 
-#if NETCORE
-            // Must run off Self Contained Deployment
-            string path = $"/assemblypath={assembly.Location.Replace(".dll", ".exe")}";
-#else
-            string path = $"/assemblypath={assembly.Location}";
+            if (currentProcess == null)
+                throw new TopshelfException("Process.GetCurrentProcess() is null for some reason.");
+
+            string path =
+                IsDotnetExe(currentProcess)
+                ? $"/assemblypath={currentProcess.MainModule.FileName} \"{assembly.Location}\""
+                : $"/assemblypath={currentProcess.MainModule.FileName}";
 
-#endif
             string[] commandLine = { path };
 
             var context = new InstallContext(null, commandLine);
@@ -171,6 +174,12 @@ static TransactedInstaller CreateTransactedInstaller(Installer installer)
             return transactedInstaller;
         }
 
+        static bool IsDotnetExe(Process process) =>
+            process
+            .MainModule
+            .ModuleName
+            .Equals("dotnet.exe", StringComparison.InvariantCultureIgnoreCase);
+
         static ServiceInstaller ConfigureServiceInstaller(HostSettings settings, string[] dependencies,
             HostStartMode startMode)
         {