LazyTensor -> LinearOperator
The LazyTensor functionality is moving to a separate repository (GitHub.com/cornellius-gp/linear_operator).
This PR deprecates LazyTensor and instead uses the LinearOperator implementation.
(Note that this PR does not change any GPyTorch code; other than removing gpytorch/lazy/*_lazy_tensor.py and all other related files. A separate PR will make changes to the code that rename all *LazyTensor references and utilize the torch_function functionality of LinearOperator).
New requirements
- Python 3.8 (was 3.7)
- Torch 1.11 (was 1.9/1.10)
The awesomeness of this is totally awesome.
@Balandat I think requiring Python 3.8 makes a lot of sense.
This is no longer a WIP PR, but let's not merge it until we merge #2037 (and put out a 1.7 release).