Allow customer handle error codes

[artemijan]

Here you raise an error with text mnessage

adyen-python-api-library/Adyen/client.py

Line 502 in 91b02d8

raise AdyenAPIValidationError(erstr)

Instead of doing this we need to raise custom error that contains not only text but the errorCode too.
This is needed to handle custom validation messages on Customer side (for example with translation).
for example

class MyException(Exception):
    def __init__(self,*args,**kwargs):
        self.code = kwargs.pop('error_code',None)
        super().__init__(*args,**kwargs)