Refactor: refactor module_container

[denghuilu]

This pull request refactors the Container Tensor, making its structure more clear and easy to grasp. Our ultimate goal is to shape the Tensor into a fundamental tool for scientific computing needs. The changes in this PR cover a few main points:

1. We've reworked the way files are organized, making it simpler to understand how the code pieces relate to each other.
2. Introduced support for move semantics to the Tensor class.
3. Excitingly, we've also plugged in the Einsum summation operation to the Tensor class. We can now harness powerful linear algebra capabilities, just like you do with LibTorch and TensorFlow. Check this for more detailed usage of this op.