[code-reflection] RFR: Second Proposal to generalize handling of Vector Types based on 644

[Juan Fumero]

This PR adds another proposal for generalising HAT Vector Types. 

It is based on PR #644 as an alternative approach. So we can evaluate each proposal and device which one to move forward. 

This approach replaces the `@HATVectorType` annotation with a set of interfaces to identify base type and width of the vector type being represented. 

For instance:


public interface _V {
    PrimitiveType type();
    int width();
}

public interface _V4 extends _V {

    @CodeReflection
    @Override
    default int width() {
        return 4;
    }
}


public interface Float4 extends _V4 {

    float x();
    float y();
    float z();
    float w();

    @CodeReflection
    @Override
    default PrimitiveType type() {
        return JavaType.FLOAT;
    }

   ...

}


Note that both methods, width and type, are annotated with `@CodeReflection`. During the "dialectify" process, this approach builds the code models for both methods and inspects the meta-data values. 

Some restrictions:

- `Float4` is not an `iFace` interface due to the small granularity. 
- Usually, these types are inspected from the kernel code, so we don't have instance objects.
- Returning `PrimitiveType` from the `type` method allows us to be restricted in the amount of base types to support. 


How to test:

For OpenCL:


HAT=SHOW_CODE,SHOW_COMPILATION_PHASES java @hat/otest ffi-opencl hat.test.TestVectorTypes


For CUDA:



HAT=SHOW_CODE,SHOW_COMPILATION_PHASES java @hat/otest ffi-cuda hat.test.TestVectorTypes


This PR has been tested with both OpenCL and CUDA backends.

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

Commit messages:
 - Merge branch 'code-reflection' into hat/vectors/generalv2
 - Merge remote-tracking branch 'refs/remotes/personal/hat/vectors/generalv2' into hat/vectors/generalv2
 - Merge remote-tracking branch 'refs/remotes/personal/hat/vectors/generalv2' into hat/vectors/generalv2
 - [hat] CUDA backend fixed
 - [hat] RW vector float4 sample added
 - [hat] missing header license added
 - [hat] Generalise vectorisation type system and dialectify for HAT v2
 - [hat] refactor for vector phases and scaffolding for vectors and interfaces
 - minor change
 - [hat] Proposal to generalise dialect for vector types
 - ... and 14 more: https://git.openjdk.org/babylon/compare/420c933a...6166cd63

Changes: https://git.openjdk.org/babylon/pull/647/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=647&range=00
  Stats: 724 lines in 25 files changed: 468 ins; 147 del; 109 mod
  Patch: https://git.openjdk.org/babylon/pull/647.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/647/head:pull/647

PR: https://git.openjdk.org/babylon/pull/647