Previously MakePackedAPI was in the target independent stage,
but never the less requires the device_type information that will be
binded at a later target dependent stage.

The previous implementation was due to the limitation of LoweredFunc
which can not carry buffer_map info(so they have to be lowered right away).
This is no longer the case after the unified IR refactor.

This PR migrates MakePackedAPI to a target dependent stage
and removes the un-necessary BindDevice pass.

This PR enables the copy on write optimizations passes:
- Enable COW for IRModule both TIR and relay passes.
- Enabled COW for PrimFunc in TIR passes.

Need more thoughts into whether/how to enable COW
for relay::Function, due to some function passes depend
on the presence of IRModule for context information,
and the std::move of the related function to nullptr
might affect the related behavior.

* [REFACTOR][TIR] Introduce ExprDeepEqual, Remove IRDeepCompare

This PR introduces ExprDeepEqual which reuses the StructuralEqual infra.
We migrated the usecases of ir_pass::Equal to ExprDeepEqual and StructuralEqual.

* Address comments

* [REFACTOR][TIR] Introduce PrimFuncPass.

- Introduce PrimFuncPass
- Convert one pass to the unified Pass API.

* Address comments

* Fix comments

* [TESTS] Triage the testcases to fit the naming convention of the new namespaces

* Remove multiple usage of system lib to avoid test problems

* [REFACTOR][PY][API-CHANGE] Remove legacy python files.

Remove legacy python files.
Use the te namespace for most of the tensor expression primitives.

- tvm.create_schedule -> tvm.te.create_schedule
- tvm.placeholder -> tvm.te.placeholder
- tvm.compute -> tvm.te.compute

* Remove top-level exposures.

- Move related files into the corresponding location as in C++
- Keep the top-level TVM API backward compatible to make minimum changes in topi

* [arith] add ShapeVar representing non-neg valued variable in a tensor shape

* bounder remover; deal with div in int_set differently

* fix bounder_remover

* migrate unittest to use shape_var

* use tvm.shape_var in integration & relay tests

* add test case; fix Var register

* fix lint

* fix lint again

* add default ShapeVar visitor in Relay

* fix override

* fix ShapeVar visit bug

* revert IntervalSet for shape_var

* remove bound_remover

* remove is_var; use constructor for shapevar/var instead

* ShapeVar -> SizeVar; add constructor comments

* shape_var -> size_var in doc

* tindex -> size

* [HEADER] ASF header dir=include

* [HEADER] ASF Header dir=src

* [HEADER] ASF Header -dir=python

* [HEADER] ASF header dir=topi

* [HEADER] ASF Header dir=nnvm

* [HEADER] ASF Header -dir=tutorials

* [HEADER] ASF Header dir=tests

* [HEADER] ASF Header -dir=docker

* fix whitespace

* [HEADER] ASF Header -dir=jvm

* [HEADER] ASF Header -dir=web

* [HEADER] ASF Header --dir=apps

* [HEADER] ASF Header --dir=vta

* [HEADER] ASF Header -dir=go

* temp

* [HEADER] ASF Header --dir=rust

* [HEADER] Add ASF Header --dir=cmake

* [HEADER] ASF Header --dir=docs

* [HEADER] Header for Jenkinsfile

* [HEADER] ASF Header to toml and md

* [HEADER] ASF Header to gradle

* Finalize rat cleanup

* Fix permission

* Fix java test

* temporary remove nnvm onnx test