Make Controller Helpers autoloadable

[mamhoff]

There's no real good reason to keep these files in lib and require them on app startup. Let's put them in app/ and let Zeitwerk handle their loading.

[kennyadsl]

I think the reason to have them in lib is to being easily loadable by host applications and extensions. Can we do the same now?

[codecov]

Codecov Report

Attention: Patch coverage is 73.47826% with 61 lines in your changes missing coverage. Please review.

Project coverage is 89.28%. Comparing base (c976eac) to head (0ef2e29).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
...pp/helpers/spree/core/controller_helpers/common.rb	0.00%	59 Missing ⚠️
...spree/core/controller_helpers/strong_parameters.rb	92.59%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6062      +/-   ##
==========================================
- Coverage   89.47%   89.28%   -0.19%     
==========================================
  Files         805      813       +8     
  Lines       17875    17906      +31     
==========================================
- Hits        15993    15987       -6     
- Misses       1882     1919      +37     

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[mamhoff]

Yes, they have the same loading characteristics as e.g. Spree::Order - available from anywhere simply by invoking the constant names.

[kennyadsl]

Right, we just don't need any require before using it now. What about keeping the files and print a warning telling people that they can remove the require now? I'm afraid this might break all stores requiring the lib files.

[mamhoff]

Right, we just don't need any require before using it now. What about keeping the files and print a warning telling people that they can remove the require now? I'm afraid this might break all stores requiring the lib files.

Good catch. I've re-added the files in lib with just a deprecation warning. There's even a test documenting what happens.

[tvdeyen]

Thanks.

[kennyadsl]

@mamhoff approved and auto-merge enabled. Once the conflict is solved, it will be merged.

[tvdeyen]

Thanks for also tackling the Rubocop todos