[1.x] [FEATURE] Add API to control denormalized computations

[bgawrych]

Description

This is implementation of RFC #19361 and connected with issue #19218

>>> import mxnet as mx
>>> mx.nd.array([9e-45])

[0.]
<NDArray 1 @cpu(0)>
>>> mx.util.set_flush_denorms(False)
>>> mx.nd.array([9e-45])

[8.e-45]
<NDArray 1 @cpu(0)>
>>> mx.util.set_flush_denorms(True)
>>> mx.nd.array([9e-45])

[0.]
<NDArray 1 @cpu(0)>
>>> exit

As stated in RFC handling denormalized values is enabled by default and API for changing this behavior is available for the user

Checklist

Essentials

• PR's title starts with a category (e.g. [BUGFIX], [MODEL], [TUTORIAL], [FEATURE], [DOC], etc)
• Changes are complete (i.e. I finished coding on this PR)
• [] All changes have test coverage
• Code is well-documented

[mxnet-bot]

Hey @bgawrych , Thanks for submitting the PR
All tests are already queued to run once. If tests fail, you can trigger one or more tests again with the following commands:

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[bgawrych]

@mxnet-bot run ci [centos-gpu, unix-gpu, windows-cpu, windows-gpu]

[mxnet-bot]

Jenkins CI successfully triggered : [unix-gpu, windows-gpu, centos-gpu, windows-cpu]

[bgawrych]

Hey @szha,
enabling FTZ and DAZ introduces CI fail in test_numpy_interoperability.py::test_np_array_ufunc_protocol

Problematic function is remainder and I'm not sure how this should be handled - should it be disabling FTZ for this test, editing workload or maybe something different?

[mxnet-bot]

Jenkins CI successfully triggered : [windows-gpu, sanity, website, clang, centos-cpu, unix-cpu, centos-gpu, unix-gpu, edge, windows-cpu, miscellaneous]

[szha]

Other than a few nits above on the documentation the change looks good to me. Thanks!

[bgawrych]

@mxnet-bot run ci [unix-gpu, unix-cpu]

[mxnet-bot]

Jenkins CI successfully triggered : [unix-gpu, unix-cpu]