Feat: add the get_licensing_config method

[bonnie57]

Description

1. Add the get_licensing_config method
2. Fix the set_licensing_config method
3. Create LicensingConfigData data class
4. Add unit tests and integration tests

Breaking change

• Modify licensing_config signature from dict to LicensingConfig in the set_licensing_config method.
• Modify return signature from dict|None to dict in the following methods:
  1. register_commercial_use_pil
  2. register_commercial_remix_pil

Test Plan

Issue

• Inconsistent argument naming in set_licensing_config method #124
• Add the get_licensing_config method #130