lnwire+discovery: rename ShortChannelIDEncoding to QueryEncoding

Since the the encoding can be used for multiple different fields, we
rename it here to be more generic.

lnwire/reply_channel_range_test.go

@@ -44,7 +44,7 @@ func TestReplyChannelRangeEmpty(t *testing.T) {
 
 	emptyChannelsTests := []struct {
 		name       string
-		encType    ShortChanIDEncoding
+		encType    QueryEncoding
 		encodedHex string
 	}{
 		{