This is intended to be used by the API Promotions Controller.

This configurable class finds a promotion by its code.

The default has to be the Null promotion finder.

The API promotions controller is pretty straightforward, and the only
touch point here is finding a promotion. With that added to the
promotion configuration, we can now use it with no changes to our specs.

This allows us to change the promotion system with factories, because we
stop using factories in this spec.

We want to extract the legacy promotion system from Solidus into its own
gem to facilitate moving towards solidus_promotions.

The new weights for the individual sub-projects are their duration in
seconds.

Previously, all flash messages were showing with the same (black)
background. Internally, the flash object converts and stores keys
as strings [1].

[1] https://github.com/rails/rails/blob/main/actionpack/lib/action_dispatch/middleware/flash.rb#L163

Add Legacy promotions gem

Add extension point: Promotion finder

The money gem in its latest iteration added a space between value and
unit of the Swiss Franc. Our heuristic in `_js_locale_data.html.erb`
can't deal with that, so we add a third branch to it: If the money gem
has a format wish, we'll respect it, but replace its abbreviations with
the one the `accounting.js` library prefers.

Fix JS locale data for release of Money 6.19

[ADMIN] Fix flash messages coloring