Added BinaryOperationsForRegistersCommand impl.

Added: BinaryOperationsForRegistersCommand (0x8XY4, 0x8XY5, 0x8XY7)
implementation.
Edited: error in Execute_WithNullRegistersValue_ExpectedResultIsNull
test from LogicalArithmeticsForRegistersCommandFixture (registersStub
isn't used for creating logicalArithmeticsForRegistersCommand).