* [REFACTOR][NODE][RUNTIME] Move Node to the new Object protocol.

This PR removes the original node system, and make node as a subclass of Object.
This is a major refactor towards a better unified runtime object system.

List of changes in the refactor:

- We now hide data_ field, use Downcast explicitly to get a sub-class object.
- Removed the node system FFI in python.
- Removed the node C API, instead use PackedFunc for list and get attrs.
- Change relay::Op::set_attr_type_key(attr_key_name) to relay::Op::set_attr_type<AttrType>().
  - This change was necessary because of the new Object registration mechanism.
  - Subsequent changes to the op registrations
  - The change revealed a few previous problems that is now fixed.
- Patched up a few missing node type registration.
  - Now we will raise an error if we register object that is not registered.
- The original node.h and container.h are kept in the same location.
- Calling convention: kObjectHandle now equals the old kNodeHandle, kNodeHandle is removed.
- IRFunctor now dispatches on ObjectRef.
- Update to the new type checking API: is_type, derived_from are replaced by IsInstance.
- Removed .hash member function, instead use C++ convention hasher functors.

* Address review comments

* [ARITH] Use explicit div/mod functions instead of operators.

* fix pooling case

* Expose llvm.nearbyint intrinsic. This is a faster alternate to rounding.

Summary:

Test Plan:

Reviewers:

Subscribers:

Tasks:

Tags:

* Added python binding. Added test.

Summary:

Test Plan:

Reviewers:

Subscribers:

Tasks:

Tags:

* add expr `isnan`

* move to intrinsic

* doc & add to topi

* fix error from ci

* [ARITH] Add Lowering rule for FloorDiv/Mod

* add comment about constant folding

* fix inconsistent python/cpp APIs for if_then_else

* fix error message

* fix power consistency

* fix

* fix bug

* add test

* [ARITH][IR] Introduce FloorDiv/Mod

* Address review comments

* address review comments, fix div sub rule

* [INFA][IR] Build and Evolve Low-level IR. Remove dep from HalideIR.


* Update include/tvm/node/ir_functor.h

Co-Authored-By: Jared Roesch <roeschinc@gmail.com>

* Update include/tvm/node/ir_functor.h

Co-Authored-By: Jared Roesch <roeschinc@gmail.com>

* Add `set_body_simple` to Registry, refactor a lot of code to use it

* Add more types to Relay PackedFuncs

* Add Registry::set_body_method to easily make Node methods into
PackedFuncs

* Add set_body_method, set_body_node_method; start typing api_lang

* Add some docs, remove unused script

* Fix mysterious linter problem

* Touch up api_ir.cc

* Fix some issues with TOPI argument counts

* Revert changes to topi.cc to avoid problems with optional arguments

* A little more cleanup

* Type more of the api _ functions

* Whitespace

* Finalize names and docs for new registry helpers

* Update docs

* [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

* Add eager simplication for FloatImm

* fix

* fix lint

* Fix gcc warning

* fix

* Add test case

* [IR] Add body to AssertStmt

* fix lint

* [LANG] Expose tvm.cast

* Update

* Add unittest

* Support for batch ComputeOp

* Support for batch ComputeOp

* Fix CrossThreadReduction

* Fix lint

* Add UpdateArray, remove support for batch reduce

* Tuple input support for reduce

* rfactor works with multiple reducer; support multiple reducers with different types

* Small fix

* Small fix

* Change return type of rfactor to Array<Expr>

* Fix lint

* Improve

* Add tutorial

* Improve tutorial

* Improve tutorial

* [LANG] CommReducer

* Reorganize c_api

* Remove InitValue and Combine; refactor Functor

* Make CommReducer an Expr

* Make comm_reducer type independent

* Make CommReducerNode a Node

* Small fix

* Refine

* Refine front api; add integration testcases for min/max

* Fix python

* Refine

* Fix lint and add example

* [LANG] Include buffer semnatics, introduce pylint

* Refactor inline add support for buffer indexing

* fix doc

* [PASS] Schedule Ops init working version

* bugfix in PassUp