websocket utf8: move utf8 functions from websocket to encoding.utf8, add utf8_test.v (4/4) (#5924)

vlib/encoding/utf8/utf8_test.v

@@ -0,0 +1,9 @@
+import encoding.utf8 { validate_str }
+
+fn test_validate_str() {
+	assert validate_str('añçá') == true
+	assert validate_str('\x61\xC3\xB1\xC3\xA7\xC3\xA1') == true
+	assert validate_str('\xC0\xC1') == false
+	assert validate_str('\xF5\xFF') == false
+	assert validate_str('\xE0\xEF') == false
+}