feat(compliance): RHINENG-8964 allow listing/assigning policies

[xiangce]

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Complete Description of Additions/Changes:

• This is a draft re-implementation of #4056 based on #4124

[LightOfHeaven1994]

Tested it with custom egg, everything works as expected! thank you @xiangce . We will need to wait before merging this one since we haven't released APIv2 fully to prod yet

[skateman]

Thank you @xiangce, I will go through this after my PTO.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 61.23596% with 69 lines in your changes missing coverage. Please review.

Project coverage is 77.17%. Comparing base (d5112e8) to head (1a2b0ad).

Files with missing lines	Patch %	Lines
...ghts/specs/datasources/compliance/compliance_ds.py	53.94%	34 Missing and 1 partial :warning:
insights/client/config.py	31.42%	23 Missing and 1 partial :warning:
insights/specs/datasources/compliance/__init__.py	83.05%	7 Missing and 3 partials :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #4209 +/- ## ========================================== - Coverage 77.20% 77.17% -0.04% ========================================== Files 764 764 Lines 41559 41638 +79 Branches 8786 8792 +6 ========================================== + Hits 32086 32133 +47 - Misses 8414 8444 +30 - Partials 1059 1061 +2 ``` | [Flag](https://app.codecov.io/gh/RedHatInsights/insights-core/pull/4209/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=RedHatInsights) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/RedHatInsights/insights-core/pull/4209/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=RedHatInsights) | `77.16% <61.23%> (-0.04%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=RedHatInsights#carryforward-flags-in-the-pull-request-comment) to find out more.

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[romanblanco]

@xiangce @skateman is this ready to be merged?

[skateman]

We have performance issues...

[xiangce]

@LightOfHeaven1994 and @Mishrasubha has helped verified this PR on local, we are good to merge this PR now.

And FYI, it will be released to PyPI next Thu, it will be available for customer to use the next next Monday.