Add an orders/cart component

[elia]

Summary

• add variants
• change quantity
• remove line-items

order.cart.mov

Checklist

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The following are mandatory for all PRs:

• I have written a thorough PR description.
• I have kept my commits small and atomic.
• I have used clear, explanatory commit messages.

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• 📖 I have updated the README to account for my changes.
• 📑 I have documented new code with YARD.
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• ✅ I have added automated tests to cover my changes.
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[codecov]

Codecov Report

Merging #5441 (a07232b) into main (d479d6a) will increase coverage by 0.05%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #5441      +/-   ##
==========================================
+ Coverage   88.91%   88.96%   +0.05%     
==========================================
  Files         614      617       +3     
  Lines       14829    14876      +47     
==========================================
+ Hits        13185    13235      +50     
+ Misses       1644     1641       -3     

Files	Coverage Δ
.../components/solidus_admin/orders/cart/component.rb	100.00% <100.00%> (ø)
...ents/solidus_admin/orders/cart/result/component.rb	100.00% <100.00%> (ø)
.../components/solidus_admin/orders/show/component.rb	100.00% <100.00%> (ø)
.../app/components/solidus_admin/ui/icon/component.rb	100.00% <100.00%> (ø)
...app/components/solidus_admin/ui/toast/component.rb	100.00% <100.00%> (ø)
...controllers/solidus_admin/line_items_controller.rb	100.00% <100.00%> (ø)
...app/controllers/solidus_admin/orders_controller.rb	100.00% <100.00%> (+27.27%)	⬆️

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[rainerdema]

🌟 Amazing work! 🌟

[tvdeyen]

Nice work, but there are some mandatory things to be updated