fix v1 plugin issue

- Settings NullReference
- ExecutablePlugin not working

Author: taooceros

Flow.Launcher.Core/Plugin/ExecutablePlugin.cs

@@ -1,5 +1,6 @@
 using System.Diagnostics;
 using System.IO;
+using System.Text.Json;
 using System.Threading;
 using System.Threading.Tasks;
 
@@ -27,14 +28,14 @@ public ExecutablePlugin(string filename)
         protected override Task<Stream> RequestAsync(JsonRPCRequestModel request, CancellationToken token = default)
         {
             // since this is not static, request strings will build up in ArgumentList if index is not specified
-            _startInfo.ArgumentList[0] = request.ToString();
+            _startInfo.ArgumentList[0] = JsonSerializer.Serialize(request, RequestSerializeOption);
             return ExecuteAsync(_startInfo, token);
         }
 
         protected override string Request(JsonRPCRequestModel rpcRequest, CancellationToken token = default)
         {
             // since this is not static, request strings will build up in ArgumentList if index is not specified
-            _startInfo.ArgumentList[0] = rpcRequest.ToString();
+            _startInfo.ArgumentList[0] = JsonSerializer.Serialize(rpcRequest, RequestSerializeOption);
             return Execute(_startInfo);
         }
     }

Flow.Launcher.Core/Plugin/JsonRPCPlugin.cs

@@ -256,7 +256,7 @@ public override async Task<List<Result>> QueryAsync(Query query, CancellationTok
                 {
                     query.Search
                 },
-                Settings.Inner);
+                Settings?.Inner);
 
             var output = await RequestAsync(request, token);