[code-reflection] RFR: [hat][proposal] ComputeRange and ThreadMesh API for defining 1D, 2D and 3D Ranges

[Juan Fumero]

This PR proposes an extension of the HAT API to leverage 1D, 2D and 3D ranges for the compute context dispatch. 
A `ComputeRange` is an entity that holds global and local thread mesh. In the future, we can add offsets to it. 

Each `ThreadMesh` is a triplet representing the number of threads for x,y, and z dimensions. 

How to dispatch 1D kernels?


ComputeRange range1D = new ComputeRange(new ThreadMesh1D(size));
cc.dispatchKernel(range1D,
                kc -> myKernel(...));


How to dispatch 2D kernels?


ComputeRange range2D = new ComputeRange(new ThreadMesh2D(size, size));
cc.dispatchKernel(range2D,
                kc -> my2DKernel(...));


How to enable local mesh? 

We pass a second parameter to the ComputeRange constructor to define local mesh. If it is not passed, then it is `null` and the HAT runtime can select a default set of values. 


ComputeRange computeRange = new ComputeRange(
        new ThreadMesh2D(globalSize, globalSize), 
        new ThreadMesh2D(16, 16));
cc.dispatchKernel(computeRange,
                kc -> matrixMultiplyKernel2D(kc, matrixA, matrixB, matrixC, globalSize)
        );


In addition, this PR renames the `KernelContext` internal API to map the context ndrange object to native memory to `KernelBufferContext`.


#### How to check? 


java @hat/run ffi-opencl matmul 1D
java @hat/run ffi-opencl matmul 2D

java @hat/run ffi-cuda matmul 1D
java @hat/run ffi-cuda matmul 2D

-------------

Commit messages:
 - [hat] Javadoc for the rest of the ComputeRange Class
 - [hat] Add threadmesh subtyping to keep consistency accross dimensions between global and local
 - [hat] ThreadBlock dispatcher enabled for the CUDA backend
 - [hat][api] Proposal for ComputeRange and ThreadMesh

Changes: https://git.openjdk.org/babylon/pull/516/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=516&range=00
  Stats: 639 lines in 18 files changed: 507 ins; 97 del; 35 mod
  Patch: https://git.openjdk.org/babylon/pull/516.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/516/head:pull/516

PR: https://git.openjdk.org/babylon/pull/516