[code-reflection] RFR: [feature][HAT] 2D and 3D ranges for the NDRange API

[Juan Fumero]

This patch introduces the concept of 2D and 3D ranges. 

This allows developers to do the following:
- Accessing 1D, 2D and 3D thread indexing within the kernels. The `KernelContext` API has been extended to do this.
- Dispatching 1D, 2D and 3D kernels via the `ComputeContext`.

**IMPORTANT**: This patch has been tested for the OpenCL backend, the CUDA backend generates correct code, but for some reason I can't dispatch it due to CUDA incompatibilities (seems to be orthogonal to this PR). I will investigate this in a separate issue. 

An example of use is provided in the `matmul/Main.java` class.

Example of 1D kernel in HAT:


@CodeReflection
    public static void matrixMultiplyKernel1D(@RO KernelContext kc, @RO F32Array matrixA, @RO F32Array matrixB, @RW F32Array matrixC, int size) {
        if (kc.x < kc.maxX) {
            for (int j = 0; j < size; j++) {
                float acc = 0;
                for (int k = 0; k < size; k++) {
                    acc += (matrixA.array(kc.x * size + k) * matrixB.array(k * size + j));
                }
                matrixC.array(kc.x * size + j, acc);
            }
        }
    }


Example of a 2D kernel:


@CodeReflection
    public static void matrixMultiplyKernel2D(@RO KernelContext kc, @RO F32Array matrixA, @RO F32Array matrixB, @RW F32Array matrixC, int size) {
        if (kc.x < kc.maxX) {
            if (kc.y < kc.maxY) {
                float acc = 0;
                for (int k = 0; k < size; k++) {
                    acc += (matrixA.array(kc.x * size + k) * matrixB.array(k * size + kc.y));
                }
                matrixC.array(kc.x * size + kc.y, acc);
            }
        }
    }


How to dispatch?

The dispatcher now has more parameters to setup the max thread size for each dimension. In the case of a 2D:


computeContext.dispatchKernel(maxX, maxY,
    kernelContext -> matrixMultiplyKernel2D(kernelContext, matrixA, matrixB, matrixC, size)
);


### How to test this patch?

I extended the test-case for the matrix multiplication. 

Run with 1D:


HAT=SHOW_CODE java @hat/run ffi-opencl matmul 1D


Run with 2D


HAT=SHOW_CODE java @hat/run ffi-opencl matmul 2D

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

Commit messages:
 - [feature] 2D and 3D ranges for the NDRange API

Changes: https://git.openjdk.org/babylon/pull/496/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=496&range=00
  Stats: 404 lines in 23 files changed: 298 ins; 23 del; 83 mod
  Patch: https://git.openjdk.org/babylon/pull/496.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/496/head:pull/496

PR: https://git.openjdk.org/babylon/pull/496