http-service: add session check call to check session validity

http-api/src/main/java/net/runelite/http/api/account/AccountClient.java

@@ -99,4 +99,28 @@ public class AccountClient
 			logger.debug("Sent logout request");
 		}
 	}
+
+	public boolean sesssionCheck()
+	{
+		HttpUrl url = RuneliteAPI.getApiBase().newBuilder()
+			.addPathSegment("account")
+			.addPathSegment("session-check")
+			.build();
+
+		logger.debug("Built URI: {}", url);
+
+		Request request = new Request.Builder()
+			.header(RuneliteAPI.RUNELITE_AUTH, uuid.toString())
+			.url(url)
+			.build();
+
+		try (Response response = RuneliteAPI.CLIENT.newCall(request).execute())
+		{
+			return response.isSuccessful();
+		}
+		catch (IOException ex)
+		{
+			return false;
+		}
+	}
 }

http-service/src/main/java/net/runelite/http/service/Service.java

@@ -92,6 +92,9 @@ public class Service implements SparkApplication
 
 			before("/logout", authFilter);
 			get("/logout", accounts::logout);
+
+			before("/session-check", authFilter);
+			get("/session-check", accounts::sessionCheck);
 		});
 		before("/config", authFilter);
 		path("/config", () ->

http-service/src/main/java/net/runelite/http/service/account/AccountService.java

@@ -249,4 +249,10 @@ public class AccountService
 
 		return "";
 	}
+
+	public Object sessionCheck(Request request, Response response)
+	{
+		// Auth filter would kick this out before here
+		return "";
+	}
 }