XHTTP XMUX: Add hMaxRequestTimes and hKeepAlivePeriod (#4163)

Fixes https://github.com/XTLS/Xray-core/discussions/4113#discussioncomment-11492833

transport/internet/splithttp/browser_client.go

@@ -13,6 +13,10 @@ import (
 // has no fields because everything is global state :O)
 type BrowserDialerClient struct{}
 
+func (c *BrowserDialerClient) IsClosed() bool {
+	panic("not implemented yet")
+}
+
 func (c *BrowserDialerClient) Open(ctx context.Context, pureURL string) (io.WriteCloser, io.ReadCloser) {
 	panic("not implemented yet")
 }