Wrap filename and param name in quotes for disposition

Author: alexeyzimarev

src/RestSharp/Request/RequestContent.cs

@@ -68,8 +68,8 @@ void AddFiles() {
                 fileContent.Headers.ContentType = MediaTypeHeaderValue.Parse(file.ContentType);
 
             fileContent.Headers.ContentDisposition = new ContentDispositionHeaderValue("form-data") {
-                Name     = file.Name,
-                FileName = file.FileName
+                Name     = $"\"{file.Name}\"",
+                FileName = $"\"{file.FileName}\""
             };
             mpContent.Add(fileContent, file.Name, file.FileName);
         }
@@ -132,7 +132,7 @@ void AddBody(bool hasPostParameters) {
             // here we must use multipart form data
             var mpContent = Content as MultipartFormDataContent ?? new MultipartFormDataContent();
             var ct        = bodyContent.Headers.ContentType?.MediaType;
-            var name      = bodyParameter!.Name.IsEmpty() ? ct : bodyParameter!.Name;
+            var name      = bodyParameter!.Name.IsEmpty() ? ct : bodyParameter.Name;
 
             if (name.IsEmpty())
                 mpContent.Add(bodyContent);

test/RestSharp.Tests.Integrated/MultipartFormDataTests.cs

@@ -34,7 +34,7 @@ public MultipartFormDataTests(ITestOutputHelper output) {
     const string ExpectedFileAndBodyRequestContent =
         "--{0}" +
         $"{LineBreak}{KnownHeaders.ContentType}: application/octet-stream" +
-        $"{LineBreak}{KnownHeaders.ContentDisposition}: form-data; name=fileName; filename=TestFile.txt" +
+        $"{LineBreak}{KnownHeaders.ContentDisposition}: form-data; name=\"fileName\"; filename=\"TestFile.txt\"" +
         $"{LineBreak}{LineBreak}This is a test file for RestSharp.{LineBreak}" +
         $"--{{0}}{LineBreak}{KnownHeaders.ContentType}: application/json; {CharsetString}" +
         $"{LineBreak}{KnownHeaders.ContentDisposition}: form-data; name=controlName" +