IF: Add IF activation to integration test framework

[heifner]

• Adds ability to activate instant finality to the integration test framework, specifically Cluster.py launch().
  • Unique BLS keys and proof-of-possession is created for each test run similar to proposer keys.
  • Added example in tests/distributed-transactions-test.py & tests/nodeos_run_test.py
  • If we are happy with this approach, it can be added to all integration tests and new cmake tests can be added that use it.
    • Currently LIB is not progressing after activation.
• Copied over eosio.bios contract from IF: Add setfinalizer action to eosio.bios reference-contracts#33 which has updated setfinalizer.
• Updated tutorials/bios-boot-tutorial/bios-boot-tutorial.py to include INSTANT_FINALITY activation.

[heifner]

Replaced by #1998