Add helper tests for creator fee config reads

[Obiajulu-gif]

This pull request adds additional unit tests to improve coverage for reading fee configuration from storage in the creator-keys contract. The new tests ensure that the read_protocol_fee_config and read_required_protocol_fee_config functions correctly return the stored configuration values.

Test coverage improvements:

• Added test_read_protocol_fee_config_returns_stored_config to verify that read_protocol_fee_config retrieves the correct stored fee configuration from persistent storage.
• Added test_read_required_protocol_fee_config_returns_stored_config to verify that read_required_protocol_fee_config retrieves the correct stored fee configuration from persistent storage.
  Closes Add read-only protocol config initialized method #89