CH-233: add support for the new subscriber filter API (which is yet not released publicly)

[nicdard]

Description

• added support for the (yet to open publicly) subscriber filter API.
• migrated the integration test to leverage our oauth configured workspace

Related Issue

#233

Motivation and Context

The change introduces useful constructs to interact with the new subscriber filter API.
This will enabled customers to use the new API as soon as released.

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.

[francoisledroff]

lgmt