Add infrastructure to support multiple execution environments

RemoteExec.Server/Configuration/ExecutionConfiguration.cs

@@ -11,4 +11,9 @@ public class ExecutionConfiguration
     /// Timeout for assembly loading requests in seconds. Default is 30 seconds.
     /// </summary>
     public int AssemblyLoadTimeoutSeconds { get; set; } = 30;
+
+    /// <summary>
+    /// Type of execution environment to use. Default is "AssemblyLoadContext".
+    /// </summary>
+    public string ExecutionEnvironment { get; set; } = "AssemblyLoadContext";
 }