Update Interfaces.sol to include ADDRESSES_PROVIDER() and LENDING_POOL()

[pygeek]

Compilation fails due to:

contracts/FlashLoanReceiverBase.sol:11:50: TypeError: Public state variable has override specified but does not override anything.
  ILendingPoolAddressesProvider public immutable override ADDRESSES_PROVIDER;
                                                 ^------^

contracts/FlashLoanReceiverBase.sol:12:33: TypeError: Public state variable has override specified but does not override anything.
  ILendingPool public immutable override LENDING_POOL;
                                ^------^

Interface needs to be updated to include ADDRESSES_PROVIDER() and LENDING_POOL()