This PR introduces more clear naming prefix for C API type codes
to avoid conflict with other packages.

We also removed TVMArray and TVMType to directly use DLTensor and DLDataType.

* [REFACTOR][OBJECT] Consoldiate NodePtr/Ref/Hash/Equal and macros to Object.

Historically, we have classes like NodePtr/Ref/HashEqual.
After unified object protocol, these names are just alias of the object counterpart.
Moreover, there are helper macros defined over the places for defining these object.

This PR consoldiate the terminologies into the corresponding ones
in the Object system so we have a clean and consistent API moving forward.

* Update include/tvm/attrs.h

Co-Authored-By: Wei Chen <ipondering.weic@gmail.com>

* fix compilation

Co-authored-by: Wei Chen <ipondering.weic@gmail.com>

* [REFACTOR][RUNTIME] Move NDArray to Object System.

Previously NDArray has its own object reference counting mechanism.
This PR migrates NDArray to the unified object protocol.

The calling convention of NDArray remained intact.
That means NDArray still has its own type_code and
its handle is still DLTensor compatible.

In order to do so, this PR added a few minimum runtime type
detection in TVMArgValue and RetValue only when the corresponding
type is a base type(ObjectRef) that could also refer to NDArray.

This means that even if we return a base reference object ObjectRef
which refers to the NDArray. The type_code will still be translated
correctly as kNDArrayContainer.
If we assign a non-base type(say Expr) that we know is not compatible
with NDArray during compile time, no runtime type detection will be performed.

This PR also adopts the object protocol for NDArray sub-classing and
removed the legacy NDArray subclass protocol.
Examples in apps/extension are now updated to reflect that.

Making NDArray as an Object brings all the benefits of the object system.
For example, we can now use the Array container to store NDArrays.

* Address review comments

* [LINT] Improve the check tool to handle ASF copyright message.

* [LINT] Remove unnecessary copyright message as per ASF requirement.

* Fix codegen hybrid

* [LINT] Broaden license checks to include html, xml

* [LINT] Fix rest of the files

* Fix notice

* [LINT] Improve check file type error message

* Implement the virtual machine

Co-Authored-By: wweic <ipondering.weic@gmail.com>

* Fix rebase build issues

* Reorganize vm.py and fix allocator bug

* Remove compiler

* Remove tests

* Remove backend/vm/vm.cc too

* Fix docs

* Fix doc

* Fix doc

* Add vm docs

* Remove change to dead_code.cc

* Remove Relay logging

* Remove reduce

* Update include/tvm/runtime/vm.h

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

* Reformat

* Update include/tvm/runtime/vm.h

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

* Address feedback

* Update include/tvm/runtime/vm.h

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

* Apply suggestions from code review

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

* Fix a couple outstanding comments

* Last couple comments

* Update include/tvm/runtime/vm.h

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

* Address code review feedback

* Fix final comment

* Address comments

* Error reporting and example

* add Const

* Explicitly delete copy assignment operator

* Fix rebase

* Pass 3rd arg to fusion

* Add support for custom NDArray memory management

Credit to @icemelon9 and @wweic

* Fix copy-paste issue

* Fix naive allocator.h

* Remove buffer field

* Apply Wei's suggestions.

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

* Fix Wei's suggestion

* Fix go rts

* Break MM dependency

* Add docs and clean up diff

* Add more docs

* Move to VM folder

* Fix lint

* Remove Go dep.

* Rename to Empty

* Address Haichen's comments