Use 'make_importable' to perform local imports in tests' code.

test/dataset/test_inmemory.py

test/dataset/test_torchdataset.py

test/metrics/test_binary_apr.py

test/metrics/test_binary_roc.py

test/metrics/test_mae_mse.py

test/metrics/test_multi_apr.py

test/metrics/test_rsquared.py

test/model/test_haiku.py

test/model/test_sksgd.py

test/model/test_tflow.py

test/model/test_torch.py

test/optimizer/test_modules.py

test/optimizer/test_regularizers.py

test/optimizer/test_tflow_optim.py

test/optimizer/test_torch_optim.py