Fix indicator box

[paskino]

Describe your changes

Removes wrong implementation of the proximal_conjugate method in IndicatorBox. Uses the implementation in the base class.

Describe any testing you have performed

Please add any demo scripts to CIL-Demos/misc/
Added unittests to test implementation of proximal conjugate in all proximable functions.

Link relevant issues

closes #1485

Checklist when you are ready to request a review

• I have performed a self-review of my code
• I have added docstrings in line with the guidance in the developer guide
• I have implemented unit tests that cover any new or modified functionality
• CHANGELOG.md has been updated with any functionality change
• Request review from all relevant developers
• Change pull request label to 'Waiting for review'

Contribution Notes

Please read and adhere to the developer guide and local patterns and conventions.

• The content of this Pull Request (the Contribution) is intentionally submitted for inclusion in CIL (the Work) under the terms and conditions of the Apache-2.0 License.
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[epapoutsellis]

If you want you can also fix the following:

• accelerated vs backend (GradientOperator, KullbackLeibler)
• raise error when lower>'upper`

I also suggest to create a new class for the lower==upper case, e.g., IndicatorSingleton. Also, it would be nice to create a separate script for each function, test_IndicatorBox, because it is difficult to have a massive script that tests all of our functions.

[paskino]

Notice that a new issue has arisen while developing the unit tests on Windows #1487

[paskino]

it would be nice to create a separate script for each function, test_IndicatorBox, because it is difficult to have a massive script that tests all of our functions.

Maybe, but currently our unit tests are a bit of a mess. In practice I added tests for proximal_conjugate of all functions.

[gfardell]

TotalVariation(backend='c') you had a comment saying it failed locally. I can't recreate this, and jenkins seems to be happy?

[gfardell]

Approved once we get to the bottom of TV C backend failing for Edo, #1487 !

[paskino]

I closed #1487 and slightly modified the unittests for the KullbackLeibler adding the 2 backends. Once CI is happy we can merge @gfardell

[paskino]

• raise error when lower>'upper`

Maybe it's worth adding the test in the init.