fix Executable plugin's JsonRPC request string

This is a fix of Executable plugin's JsonRPC request string for ProcessStartInfo, but tested and should be used specifically for Typescript + JavaScript plugin

Author: jjw24

Flow.Launcher.Core/Plugin/ExecutablePlugin.cs

@@ -1,5 +1,4 @@
-using System;
-using System.Diagnostics;
+using System.Diagnostics;
 using System.IO;
 using System.Threading;
 using System.Threading.Tasks;
@@ -22,17 +21,22 @@ public ExecutablePlugin(string filename)
                 RedirectStandardOutput = true,
                 RedirectStandardError = true
             };
+            
+            // required initialisation for below request calls 
+            _startInfo.ArgumentList.Add(string.Empty);
         }
 
         protected override Task<Stream> RequestAsync(JsonRPCRequestModel request, CancellationToken token = default)
         {
-            _startInfo.Arguments = $"\"{request}\"";
+            // since this is not static, request strings will build up in ArgumentList if index is not specified
+            _startInfo.ArgumentList[0] = request.ToString();
             return ExecuteAsync(_startInfo, token);
         }
 
         protected override string Request(JsonRPCRequestModel rpcRequest, CancellationToken token = default)
         {
-            _startInfo.Arguments = $"\"{rpcRequest}\"";
+            // since this is not static, request strings will build up in ArgumentList if index is not specified
+            _startInfo.ArgumentList[0] = rpcRequest.ToString();
             return Execute(_startInfo);
         }
     }