Xray-core: Forbid unencrypted outbounds on public Internet for VLESS and Trojan; Remove "none/zero/plain" for VMess and Shadowsocks (#6303)

https://github.com/XTLS/Xray-core/pull/5640#issuecomment-4611416512
https://github.com/XTLS/Xray-core/pull/6303#issuecomment-4668055274

---------

Co-authored-by: Meow <197331664+Meo597@users.noreply.github.com>

proxy/shadowsocks/config.go

@@ -85,8 +85,6 @@ func (a *Account) getCipher() (Cipher, error) {
 			IVBytes:         32,
 			AEADAuthCreator: createXChaCha20Poly1305,
 		}, nil
-	case CipherType_NONE:
-		return NoneCipher{}, nil
 	default:
 		return nil, errors.New("Unsupported cipher.")
 	}
@@ -186,30 +184,6 @@ func (c *AEADCipher) DecodePacket(key []byte, b *buf.Buffer) error {
 	return nil
 }
 
-type NoneCipher struct{}
-
-func (NoneCipher) KeySize() int32 { return 0 }
-func (NoneCipher) IVSize() int32  { return 0 }
-func (NoneCipher) IsAEAD() bool {
-	return false
-}
-
-func (NoneCipher) NewDecryptionReader(key []byte, iv []byte, reader io.Reader) (buf.Reader, error) {
-	return buf.NewReader(reader), nil
-}
-
-func (NoneCipher) NewEncryptionWriter(key []byte, iv []byte, writer io.Writer) (buf.Writer, error) {
-	return buf.NewWriter(writer), nil
-}
-
-func (NoneCipher) EncodePacket(key []byte, b *buf.Buffer) error {
-	return nil
-}
-
-func (NoneCipher) DecodePacket(key []byte, b *buf.Buffer) error {
-	return nil
-}
-
 func passwordToCipherKey(password []byte, keySize int32) []byte {
 	key := make([]byte, 0, keySize)