Mask base64 values of secrets in pipeline logs

[MantavyaDh]

Purpose of this Change

This PR enables masking of base64 encoding of secret in the pipeline logs.

What Changed

Added the base64 encoded secret to the existing secret masker along with possible escape sequence characters.

Testing

• Ensured that the new changes are used for Secret masking using the help of debugger.
• Verified that the secret and its base64 encoded value is properly masked for corner cases such as:
  • Strings containing special characters such as *, & , ! , @ , # , $ , % , ^ , & , ( , ) etc.
  • Empty secret
  • Strings containing escape sequences such as \r, \n, etc.
  • Strings which are percent (%) encoded, eg: %AZP25, %0D etc.
  • Strings which leading or tailing whitespaces.