DNAC 2.3.5 now supports AES Encrypted Authentication -- authorization header field needs updated

[jhawker09]

Prerequisites

• Have you tested the operation in the API directly?
• Do you have the latest SDK version?
• Review the compatibility matrix before opening an issue.

Describe the bug
Access token fails when using AES Encrypted Authentication, currently encoded_auth accepts base64 and authentication.py prepends b'Basic ' to encoded_auth in the request header. Likely need an additional arg for if AES encryption is enabled to NOT prepend b'Basic'.

Expected behavior
If using AES Encrypted Authentication, DNAC accepts the following string: "CSCO-AES-256 credentials=Base64Encode(AESEncrypt(username:password , aes256 key))"
Source: https://developer.cisco.com/docs/dna-center/#!authentication-and-authorization/aes-key-encryption
Final encoded_auth string should look like this (i.e. does not contain "Basic"): "CSCO-AES-256 credentials=[Base64 encoded AES encrypted username:password pair]"

Environment (please complete the following information):

• Cisco DNA Center Version and patch: Version 2.3.5.3-70194
• Python version: 3.11.4
• SDK version: dnacentersdk==2.6.5
• OS Version: MacOS 13.4.1