Remove dirty fix

[panebinese]

related #43, #61 and #62.

• fix Smock v2 bug
  • Smock v2 has a bug while generating FakeContractFactory from ContractFactory made by ethers.getContractFactory of the hardhat runtime environment with the library linking option.
  • Post an issue for this bug and encourage to fix it.
  • There should be a repository for reproduction.
• remove the dirty fix
  • There are codes for avoiding the above bug.
  • The fix resides in the test directory, begins with BEGIN DIRTY-FIX and end with END DRITY-FIX.
  • This dirty fix must be eliminated after the Smock team fixed the bug.

[panebinese]

The situation could be caused by library resolution trouble that is discussed in here
and should be investigated.