[clojure][generator][WIP] add random namespace generation

[Chouffe]

PR moved here: #14800

Description

Split random functions in their own generated namespace.

• ndarray_random_api
• symbol_random_api

It renames the following functions to be as close as possible to the scala names:

• -random-randint into randint
• sample-randint into randint-likefor instance and put them under ndarray-random-api namespace.

TODO

• Unify random and sample functions (mu vs loc and sigma)

Checklist

Essentials

Please feel free to remove inapplicable items for your PR.

• The PR title starts with [MXNET-$JIRA_ID], where $JIRA_ID refers to the relevant JIRA issue created (except PRs with tiny changes)
• Changes are complete (i.e. I finished coding on this PR)
• All changes have test coverage:
• Unit tests are added for small changes to verify correctness (e.g. adding a new operator)
• Nightly tests are added for complicated/long-running ones (e.g. changing distributed kvstore)
• Build tests will be added for build configuration changes (e.g. adding a new build option with NCCL)
• Code is well-documented:
• For user-facing API changes, API doc string has been updated.
• For new C++ functions in header files, their functionalities and arguments are documented.
• For new examples, README.md is added to explain the what the example does, the source of the dataset, expected performance on test set and reference to the original paper if applicable
• Check the API doc at http://mxnet-ci-doc.s3-accelerate.dualstack.amazonaws.com/PR-$PR_ID/$BUILD_ID/index.html
• To the my best knowledge, examples are either not affected by this change, or have been fixed to be compatible with this change

Changes

• Feature1, tests, (and when applicable, API doc)
• Feature2, tests, (and when applicable, API doc)

Comments

• If this change is a backward incompatible change, why must this change be made.
• Interesting edge cases to note here

[Chouffe]

cc @kedarbellare :-)

[kedarbellare]

looks like a great start! there are a few things to change:

1. DRY the code a bit (to share as much as possible between symbol/ndarray api and random api)
2. call the scala SymbolRandomAPI and NDArrayRandomAPI
3. unify the random_ and sample_ methods (and remove them from the ndarray/symbol api namespaces)
4. add unit tests

[kedarbellare]

the scala package does it for both random_ and sample_ (see: https://github.com/apache/incubator-mxnet/blob/master/scala-package/macros/src/main/scala/org/apache/mxnet/GeneratorBase.scala#L180).

[kedarbellare]

we should use the SymbolRandomAPI instead (see: http://mxnet.incubator.apache.org/api/scala/docs/index.html#org.apache.mxnet.SymbolRandomAPI$)

[Chouffe]

I could not get it to work. Do you have any pointers on how this should be done?

[Chouffe]

@kedarbellare

1. Done
2. I could not get this to work when calling directly the NDArrayRandomAPI and the SymbolRandomAPI
3. This is not done yet. I am not entirely sure how to do that. Can it be done in a subsequent PR?
4. Done

[Chouffe]

cc @gigasquid for feedback on the generator namespace. I am not yet comfortable with the code there ^^

[Chouffe]

I reopened a PR here: #14800

[roywei]

@mxnet-label-bot add [Clojure, pr-work-in-progress]