Fix and clean up code for mean and sum functions.

[Iainmon]

• Fix issue with sum and mean functions on tensors.
• Add dynamic shape functionality for dynamicTensor
• Add squeeze, reshape, and unsqueeze methods to dynamicTensor.

[Iainmon]

Still needs some work but I want to get this merged ASAP.

[Iainmon]

All tests that should pass, pass:

(.venv) ➜  correspondence git:(im-dev) python3 correspondence.py                                                                                 
🌱 activation/rrelu
🌱 activation/gelu
🌱 activation/hardtanh
🌱 activation/silu
🌱 activation/celu
🌱 activation/softsign
🌱 activation/softplus
🌱 activation/leakyrelu
🌱 activation/softshrink
🌱 activation/selu
🌱 activation/tanhshrink
🌱 activation/mish
🌱 activation/threshold
🌱 activation/tanh
🌱 activation/hardshrink
🌱 activation/relu
🌱 activation/sigmoid
🌱 activation/logsigmoid
🌱 activation/elu
🌱 activation/hardswish
🌱 activation/relu6
🌱 reduction/mean
🌱 reduction/sum
🌱 construction/arange
🌱 construction/ones
✅ activation/rrelu
✅ activation/gelu
✅ activation/hardtanh
✅ activation/silu
✅ activation/celu
✅ activation/softsign
❌ activation/softplus
❌ activation/leakyrelu
✅ activation/softshrink
✅ activation/selu
✅ activation/tanhshrink
❌ activation/mish
✅ activation/threshold
✅ activation/tanh
✅ activation/hardshrink
✅ activation/relu
❌ activation/sigmoid
❌ activation/logsigmoid
✅ activation/elu
❌ activation/hardswish
✅ activation/relu6
✅ reduction/mean
✅ reduction/sum
✅ construction/arange
✅ construction/ones
Failed Chapel compilations tests: []
Failed Python tests: []
Tests to fix: ['softplus', 'leakyrelu', 'mish', 'sigmoid', 'logsigmoid', 'hardswish']