"driver" normally refers to the "main" function.
Rationale: the header exposes set of APIs to drive compilation
and should be named as driver api to best reflect its usage.

Bring up namespace te -- Tensor expression language DSL.

* [REFACTOR][TYPE] Finish move all types to IR.

- Move definition of Ref and TensorType to ir
- Move type_functor.h to public header.
- Rename RefType -> RelayRefType for clarity.

* Add atol

This PR moves the codegen related code into the target folder,
as they are target specific functionalities.

We also adopt the term "compiler driver" in common compiler infra
such as rust, GHC and clang.
As a result, build_module is moved into the driver folder.

Move the conversion extensions to the specific class definitions
so that we longer need to include packed_func_ext.

* [REFACTOR] introduce top - Tensor Operation DSL.

Historically we put Tensor, Schedule and compute under the root tvm namespace.
This is no longer a good idea as the project's scope grows larger
than the tensor operation DSL.

This PR introduces top -- a namespace for tensor operational
DSL concepts such as schedule, tensor, compute.
We moved the related files to the new top subfolder.

* Move relevant files into include/tvm/top and src/top

dtype.h -> runtime/data_type.h

Changes:
- Rename all old reference of tvm::Type to DataType
- ExprNode.type -> ExprNode.dtype
- Expr.type() -> Expr.dtype()
- Change Expr related functions to expr_operator.
  - DataType::min() -> min_value(DataType)
  - DataType::max() -> max_value(DataType)
- Move type constructor Int, UInt, Float, Handle, Bool into DataType.
  - Int(bits) -> DataType::Int(bits)
  - UInt(bits) -> DataType::UInt(bits)

* Enable set_input_zero_copy in GraphRuntime

* Fix LoadParams

* Fix

* lint

* Fix remote context issue

* Fix

* Remove LOG

* Remove unused variables

* Add tests

* works

* More test scenarios

* make it simpler

* Remove unnecessary changes

* Address comments

* More comments

* Address comments

* Fix build

* [Relay] C++ Build module

* asdf