BizHawk#4187 Add a method to the comm LUA library to allow setting ExpectContinue

Author: reversefold

src/BizHawk.Client.Common/Api/HttpCommunication.cs

@@ -20,6 +20,8 @@ public sealed class HttpCommunication
 
 		public int Timeout { get; set; }
 
+		public bool ExpectContinue { get; set; } = true;
+
 		public HttpCommunication(Func<byte[]> takeScreenshotCallback, string getURL, string postURL)
 		{
 			_takeScreenshotCallback = takeScreenshotCallback;
@@ -49,6 +51,7 @@ public async Task<string> Get(string url)
 		public async Task<string> Post(string url, FormUrlEncodedContent content)
 		{
 			_client.DefaultRequestHeaders.ConnectionClose = true;
+			_client.DefaultRequestHeaders.ExpectContinue = ExpectContinue;
 			HttpResponseMessage response;
 			try
 			{

src/BizHawk.Client.Common/lua/CommonLibs/CommLuaLibrary.cs

@@ -231,6 +231,13 @@ public void HttpSetGetUrl(string url)
 			APIs.Comm.HTTP.GetUrl = url;
 		}
 
+		[LuaMethod("httpSetExpectContinue", "Set ExpectContinue boolean to an explicit value")]
+		public void HttpSetExpectContinue(bool value)
+		{
+			CheckHttp();
+			APIs.Comm.HTTP.ExpectContinue = value;
+		}
+
 		[LuaMethod("httpGetPostUrl", "Gets HTTP POST URL")]
 		public string HttpGetPostUrl()
 		{
@@ -245,6 +252,13 @@ public string HttpGetGetUrl()
 			return APIs.Comm.HTTP?.GetUrl;
 		}
 
+		[LuaMethod("httpGetExpectContinue", "Get ExpectContinue value")]
+		public bool HttpGetExpectContinue()
+		{
+			CheckHttp();
+			return APIs.Comm.HTTP.ExpectContinue;
+		}
+
 		private void CheckHttp()
 		{
 			if (APIs.Comm.HTTP == null)