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] Move support related code to include/tvm/support

- tvm/logging.h -> tvm/support/logging.h
- remove tvm/base.h, move with into tvm/support/with.h

* src/common -> src/support

This PR moves attrs.h into the ir folder as it
can serve as a common infra for building ir dats structures.

We also moved common container(FloatImm) into ir/expr.h

* [REFACTOR][IR] Unify IntImm and UIntImm

This PR unifies UIntImm and IntImm to simplify the codebase.
Unsigned integer constants will also be stored as IntImm.

For uint constant that does not fit into int64(rare case), we introduced
an intrinsic tvm_big_uint_imm to construct such intgers by its
lower and higher 32bits.

* [REFACTOR][IR] Remove UIntImm to use IntImm

* rename big->large

- Use consistent constructor style to construct objects.
- Move env_func to ir as it is mainly used to construct IRs.
- Make docs consistent.

Move the relay's pass Infra to ir.
Keep FunctionPass in relay as it is local to the dialect.

We will use a single ErrorReporter to report errors during
program transformations.

This PR brings relay::Module as the unified IRModule structure.
IRModule will be used as the basic unit for transformations
through out the stack.

- Rename relay::Module -> IRModule
- Move relay/module.h -> ir/module.h
- ModuleNode::FromExpr -> IRModule::FromExpr
- FromText -> IRModule::FromText

This PR migrates relay's Op into the ir folder.
Op and its registry provides an useful mechanism to
store any attribute meta-data of an operator include
function signatures, lowering rules, side effect etc.

These features are not only useful for Relay, but also needed in the low-level IR.
At the current moment, intrinsic functions in the low-level IR are simply
represented by a string. This means we cannot type-check the low-level IR
when the type does not meet the constraint, nor can we obtain further
information such as side-effect and read write relation of these intrinsics
wrt to arguments.

Op will be used as the way to handle primitive ops(in DL terminology)
(builtin intrinsics or in compiler terminology).
We will perform follow-up refactors to make low-level CallNode
take Op as the function argument.

This PR moves a few base types from relay and low-level Expr into the ir sub-folder.
These classes will serve as a common type system across the stack.

Rationale:

- PrimExpr for low-level expressions
- RelayExpr for advanced features, including Function definition.
- Introduce BaseFunc to host all functions, including future PrimFunc(low-level expr functions, subject to discussion).

This is a minimum change we can do to unify the classes into a common hierarchy.
The main data structure that are variant specific will still be kept in the sub-namespaces.
We only include classes that is needed to allow a common Module class.
- BaseFunc
- GlobalVar
- Type definition part of ADT

We will only need the BaseFunc and their checked_type to decide the calling convention
across the function variants.

This PR moves a few base types from relay to the ir sub-folder.
These types will serve as a common type system across the stack.

Notably, we want to be able to use the same FuncType for all function signatures.
I tried to make a minimum move to bring the necessary dependencies for a FuncType.
We can discuss what additional things we want to move as a follow-up.

Notably, because the TensorType will have a dependency on low-level Expr,
we will need to break the type.h into two files and introduce a
tensor_type.h(or leave them in relay for now).