Add unit tests for Royalty module

[bonnie57]

1-13: Run python SDK unit test.

1. Run first time using 0x2560 from Yao
   1. pytest -m unit deselected all test cases.
   2. pytest -m integration deselected all test cases.
   3. pytest
      1. 4 cases failed:
         1. tests/integration/test_integration_group.py::TestCollectRoyaltyAndClaimReward::test_collect_royalties
         2. tests/integration/test_integration_group.py::TestCollectRoyaltyAndClaimReward::test_claim_reward
         3. tests/integration/test_integration_group.py::TestCollectRoyaltyAndClaimReward::test_collect_and_distribute_group_royalties
         4. tests/integration/test_integration_group.py::TestCollectRoyaltyAndClaimReward::test_get_claimable_reward
2. Run second time using 0x5B07 which Bonnie transferred 100 IPs and instructed me to mint 100 ERC20 tokens on the webpage. (Bonnie guess those fail maybe cause by the address leak ERC20 tokens.)
   1. Still have above 4 failed.