Make changing the language work

[mamhoff]

There were a few things that needed to be done here:

• Add stimulus attributes to the form in the footer
• Fix the stimulus controller to actually run the submit function
• Fix the cart link controller to consider a cart link stale if the locale changes
• Fix the link to cart component to translate the string "Cart"

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 95.99%. Comparing base (2a1f838) to head (67edde5).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #368 +/- ## ======================================= Coverage 95.99% 95.99% ======================================= Files 207 207 Lines 4874 4874 ======================================= Hits 4679 4679 Misses 195 195 ```

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