Merge branch 'feature/quant_activation_tests' of github.com:quetric/finn into feature/quant_activation_tests

Scaled and non-scaled QuantHardTanh activation tests separated. Non-scaled test includes cases with scale parameter == 1. In scaled test, bipolar activation is excluded as it's not currently supported

Add a topological order check analysis pass

ModelWrapper helper functions to find consumers/producers/direct predecessors and sucessors

use None in util fxn to indicate no file output

Add new test cases for QuantHardTanh. Cases for max > 1 and scaling_impl_type == ScalingImplType.PARAMETER with learned scale