feat: add management commands from MODULES and SUBMODULES to help

[mikicz]

Linked Issues

Fixes #10

Description

Prints help for commands in modules / submodules.

Checklist

• I have read and followed the project's Code of Conduct and Contributing Guide.
• I have checked that similar PRs have not been created before.
• I have performed a self-review of my code.
• I have added tests covering my fix or feature implementation.
• I have made corresponding changes to the documentation.
• New and existing unit tests pass locally with my changes.
• Any dependent changes have been merged and published in downstream modules.

[codecov]

Codecov Report

Attention: Patch coverage is 81.57895% with 7 lines in your changes missing coverage. Please review.

Project coverage is 96.74%. Comparing base (9bf5ce4) to head (af982da).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/management_commands/core.py	78.78%	5 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##              main      #11      +/-   ##
===========================================
- Coverage   100.00%   96.74%   -3.26%     
===========================================
  Files            5        5              
  Lines          178      215      +37     
  Branches        32       44      +12     
===========================================
+ Hits           178      208      +30     
- Misses           0        5       +5     
- Partials         0        2       +2     

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