[hat] Proposal for bfloat16

[jjfumero]

This PR introduces the type bfloat16 for HAT.

Testing for OpenCL:

HAT=SHOW_CODE java -cp hat/job.jar hat.java test ffi-opencl hat.test.TestBFloat16Type

Testing for CUDA:

HAT=SHOW_CODE java -cp hat/job.jar hat.java test ffi-cuda hat.test.TestBFloat16Type

Some tests are expecting to fail due to precision error. We will need to improve the type conversion with round-to-nearest-even for example.

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Progress

• Change must not contain extraneous whitespace

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/babylon.git pull/716/head:pull/716
$ git checkout pull/716

Update a local copy of the PR:
$ git checkout pull/716
$ git pull https://git.openjdk.org/babylon.git pull/716/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 716

View PR using the GUI difftool:
$ git pr show -t 716

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/babylon/pull/716.diff

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[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.