[FEATURE] Add asbytes method to ndarray

[ghost]

Description

The asbytes method is equivalent to numpy's tobytes . This method can be used for a variety of purposes.

Checklist

Essentials

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

Changes

• [x] Add asbytes method to ndarray

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