clean up dial functions

* add a context to all Dial functions
* remove the explicit Dial{*}Context functions

integrationtests/self/drop_test.go

@@ -97,6 +97,7 @@ var _ = Describe("Drop Tests", func() {
 				}()
 
 				conn, err := quic.DialAddr(
+					context.Background(),
 					fmt.Sprintf("localhost:%d", proxy.LocalPort()),
 					getTLSClientConfig(),
 					getQuicConfig(nil),