Add support for "decrypt_password" engine method

Please add support for the decrypt_password engine method.

[decrypt_password method](https://help.alteryx.com/developer/current/Python/use/AlteryxEngineClass.htm?Highlight=decrypt_password)
```
decrypt_password
Returns a string of encrypted or decrypted text. Works with user and machine encryption.

decrypt_password(encrypted_password, mode) -> str :
encrypted_password: The text to be treated.

Supported options include:
0: Decrypt.
2: Machine encryption
3: User encryption
```